diff --git a/src/grammar.y b/src/grammar.y
index 3e9bc44..dba555d 100644
--- a/src/grammar.y
+++ b/src/grammar.y
@@ -21,7 +21,7 @@
 //%define api.location.type {location_t}
 %locations
 %union {
-        int integ;
+        //int integ;
         char * words;
 }
 
@@ -34,7 +34,7 @@
 %token <words> T_BOOLEAN        203
 %token <words> T_CHARACTER      204
 %token <words> T_STRING         205
-%token <integ> C_INTEGER        301
+%token <words> C_INTEGER        301
 %token <words> C_NULL           302
 %token <words> C_CHARACTER      303
 %token <words> C_STRING         304
@@ -180,8 +180,10 @@ rec_op :
 
 expression:
 
-          constant {printf("constant expression\n");}
-        | SUB_OR_NEG expression %prec UMINUS {printf("negative expression\n");}
+          constant {printf("constant expression\n");} {$$ = $<words>1;}
+        | SUB_OR_NEG expression {if(strcmp($2,integer) != 0) {printf("cant negate something not an integer at 
+	line %d and column %d\n",@2.first_line,@2.first_column);}} %prec UMINUS {printf("negative expression\n");}
+
         | NOT expression {printf("not expression\n");}
         | expression ADD expression {printf("add expression\n");}
         | expression SUB_OR_NEG expression {printf("subtract expression\n");}
@@ -215,12 +217,12 @@ memOp:
 
 
 constant:
-          C_STRING
-        | C_INTEGER
-        | C_NULL
-        | C_CHARACTER
-        | C_TRUE
-        | C_FALSE
+          C_STRING {$$ = $<words>1;}
+        | C_INTEGER {$$ = $<words>1;}
+        | C_NULL {$$ = $<words>1;}
+        | C_CHARACTER {$$ = $<words>1;}
+        | C_TRUE {$$ = $<words>1;}
+        | C_FALSE {$$ = $<words>1;}
         ;
 
 types:
diff --git a/src/lexicalStructure.lex b/src/lexicalStructure.lex
index eac2840..91fc789 100644
--- a/src/lexicalStructure.lex
+++ b/src/lexicalStructure.lex
@@ -36,10 +36,10 @@ SCHAR \\n|\\t|\\\"|[^\"\n\\]
 
 %%
 
-"integer"        {if(DEBUG) {printf( "T_INTEGER:    %s  (%d)\n", yytext, T_INTEGER);}       else {if(tok_flag != NULL){print_tok(T_INTEGER);}incr(line_number,column_number,T_INTEGER);yylval.words = strdup(yytext);return T_INTEGER;}}
-"address"        {if(DEBUG) {printf( "T_ADDRESS:    %s  (%d)\n", yytext, T_ADDRESS);}       else {if(tok_flag != NULL){print_tok(T_ADDRESS);}incr(line_number,column_number,T_ADDRESS);yylval.words = strdup(yytext);return T_ADDRESS;}}
-"Boolean"        {if(DEBUG) {printf( "T_BOOLEAN:    %s  (%d)\n", yytext, T_BOOLEAN);}       else {if(tok_flag != NULL){print_tok(T_INTEGER);}incr(line_number,column_number,T_INTEGER);yylval.words = strdup(yytext);return T_BOOLEAN;}}
-"character"      {if(DEBUG) {printf( "T_CHARACTER:  %s  (%d)\n", yytext, T_CHARACTER);}     else {if(tok_flag != NULL){print_tok(T_CHARACTER);}incr(line_number,column_number,T_CHARACTER);yylval.words = strdup(yytext);return T_CHARACTER;}}
+"integer"        {if(DEBUG) {printf( "T_INTEGER:    %s  (%d)\n", yytext, T_INTEGER);}       else {if(tok_flag != NULL){print_tok(T_INTEGER);}incr(line_number,column_number,T_INTEGER);yylval.words = strdup("type");return T_INTEGER;}}
+"address"        {if(DEBUG) {printf( "T_ADDRESS:    %s  (%d)\n", yytext, T_ADDRESS);}       else {if(tok_flag != NULL){print_tok(T_ADDRESS);}incr(line_number,column_number,T_ADDRESS);yylval.words = strdup("type");return T_ADDRESS;}}
+"Boolean"        {if(DEBUG) {printf( "T_BOOLEAN:    %s  (%d)\n", yytext, T_BOOLEAN);}       else {if(tok_flag != NULL){print_tok(T_INTEGER);}incr(line_number,column_number,T_INTEGER);yylval.words = strdup("type");return T_BOOLEAN;}}
+"character"      {if(DEBUG) {printf( "T_CHARACTER:  %s  (%d)\n", yytext, T_CHARACTER);}     else {if(tok_flag != NULL){print_tok(T_CHARACTER);}incr(line_number,column_number,T_CHARACTER);yylval.words = strdup("type");return T_CHARACTER;}}
 
 "while"          {if(DEBUG) {printf( "WHILE:        %s  (%d)\n", yytext, WHILE);}           else {if(tok_flag != NULL){print_tok(WHILE);}incr(line_number,column_number,WHILE);return WHILE;}}
 "if"             {if(DEBUG) {printf( "IF:           %s  (%d)\n", yytext, IF);}              else {if(tok_flag != NULL){print_tok(IF);}incr(line_number,column_number,IF);return IF;}}
@@ -72,9 +72,9 @@ SCHAR \\n|\\t|\\\"|[^\"\n\\]
 ","              {if(DEBUG) {printf( "COMMA:        %s  (%d)\n", yytext, COMMA);}           else {if(tok_flag != NULL){print_tok(COMMA);}incr(line_number,column_number,COMMA);return COMMA;}}
 "->"             {if(DEBUG) {printf( "ARROW:        %s  (%d)\n", yytext, ARROW);}           else {if(tok_flag != NULL){print_tok(ARROW);}incr(line_number,column_number,ARROW);return ARROW;}}
 
-{DIGIT}+         {if(DEBUG) {printf( "C_INTEGER:    %s  (%d)\n", yytext, C_INTEGER);}       else {if(tok_flag != NULL){print_tok(C_INTEGER);}incr(line_number,column_number,C_INTEGER);yylval.integ = atoi(yytext);return C_INTEGER;}}
-'{CHAR}'         {if(DEBUG) {printf( "C_CHARACTER:  %s  (%d)\n", yytext, C_CHARACTER);}     else {if(tok_flag != NULL){print_tok(C_CHARACTER);}incr(line_number,column_number,C_CHARACTER);return C_CHARACTER;}}
-\"{SCHAR}*\"     {if(DEBUG) {printf( "C_STRING:     %s  (%d)\n", yytext, C_STRING);}        else {if(tok_flag != NULL){print_tok(C_STRING);}incr(line_number,column_number,C_STRING);return C_STRING;}}
+{DIGIT}+         {if(DEBUG) {printf( "C_INTEGER:    %s  (%d)\n", yytext, C_INTEGER);}       else {if(tok_flag != NULL){print_tok(C_INTEGER);}incr(line_number,column_number,C_INTEGER);yylval.words = strdup("integer");return C_INTEGER;}}
+'{CHAR}'         {if(DEBUG) {printf( "C_CHARACTER:  %s  (%d)\n", yytext, C_CHARACTER);}     else {if(tok_flag != NULL){print_tok(C_CHARACTER);}incr(line_number,column_number,C_CHARACTER);yylval.words = strdup("character");return C_CHARACTER;}}
+\"{SCHAR}*\"     {if(DEBUG) {printf( "C_STRING:     %s  (%d)\n", yytext, C_STRING);}        else {if(tok_flag != NULL){print_tok(C_STRING);}incr(line_number,column_number,C_STRING);yylval.words = strdup("string");return C_STRING;}}
 {COMMENT}        {if(DEBUG) {printf( "COMMENT:      %s  (%d)\n", yytext, COMMENT);}         else {if(tok_flag != NULL){print_tok(COMMENT);}incr(line_number,column_number,COMMENT);/*return COMMENT;*/}}
 
 "("              {if(DEBUG) {printf( "L_PAREN:      %s  (%d)\n", yytext, L_PAREN);}         else {if(tok_flag != NULL){print_tok(L_PAREN);}incr(line_number,column_number,L_PAREN);return L_PAREN;}}
@@ -84,9 +84,9 @@ SCHAR \\n|\\t|\\\"|[^\"\n\\]
 "{"              {if(DEBUG) {printf( "L_BRACE:      %s  (%d)\n", yytext, L_BRACE);}         else {if(tok_flag != NULL){print_tok(L_BRACE);}incr(line_number,column_number,L_BRACE);return L_BRACE;}}
 "}"              {if(DEBUG) {printf( "R_BRACE:      %s  (%d)\n", yytext, R_BRACE);}         else {if(tok_flag != NULL){print_tok(R_BRACE);}incr(line_number,column_number,R_BRACE);return R_BRACE;}}
 
-"true"           {if(DEBUG) {printf( "C_TRUE:       %s  (%d)\n", yytext, C_TRUE);}          else {if(tok_flag != NULL){print_tok(C_TRUE);}incr(line_number,column_number,C_TRUE);yylval.words = strdup(yytext);return C_TRUE;}}
-"false"          {if(DEBUG) {printf( "C_FALSE:      %s  (%d)\n", yytext, C_FALSE);}         else {if(tok_flag != NULL){print_tok(C_FALSE);}incr(line_number,column_number,C_FALSE);yylval.words = strdup(yytext);return C_FALSE;}}
-"null"           {if(DEBUG) {printf( "C_NULL:       %s  (%d)\n", yytext, C_NULL);}          else {if(tok_flag != NULL){print_tok(C_NULL);}incr(line_number,column_number,C_NULL);yylval.words = strdup(yytext);return C_NULL;}}
+"true"           {if(DEBUG) {printf( "C_TRUE:       %s  (%d)\n", yytext, C_TRUE);}          else {if(tok_flag != NULL){print_tok(C_TRUE);}incr(line_number,column_number,C_TRUE);yylval.words = strdup("Boolean");return C_TRUE;}}
+"false"          {if(DEBUG) {printf( "C_FALSE:      %s  (%d)\n", yytext, C_FALSE);}         else {if(tok_flag != NULL){print_tok(C_FALSE);}incr(line_number,column_number,C_FALSE);yylval.words = strdup("Boolean");return C_FALSE;}}
+"null"           {if(DEBUG) {printf( "C_NULL:       %s  (%d)\n", yytext, C_NULL);}          else {if(tok_flag != NULL){print_tok(C_NULL);}incr(line_number,column_number,C_NULL);yylval.words = strdup("address");return C_NULL;}}
 
 {ID}             {if(DEBUG) {printf( "ID:           %s  (%d)\n", yytext, ID);}              else {if(tok_flag != NULL){print_tok(ID);}incr(line_number,column_number,ID);yylval.words = strdup(yytext); return ID;}}