%{
int flag=0;
%}
%%
[(] {flag++;}
[)] {flag--;}
[\n] {if(flag==0)
printf("\t Well formed parathensis"); else if(flag>0)
printf("\t Closing parathens missing"); else
printf("\topening parathens missing");
}
%%
 
int main(void)
{
printf("enter the expression"); yylex();
return(0);
}
int yywrap(void)
{
return 0;
}
int yyerror(void)
{
printf("Error\n"); exit(1);
}