%{
#include <stdio.h>
int flag = 0;

// Required to avoid linker error on macOS
int yywrap() {
    return 1;
}
%}

%%

[a-z0-9_]+@[a-z]+\.com     { flag = 1; }

%%

int main() {
    yylex();
    if (flag == 1)
        printf("This email is accepted\n");
    else
        printf("This email is not accepted\n");
    return 0;
}