testing_program

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    char alpha_bin[4096];
    char invalid[]="BINSHbinsh";
    int i;

    scanf("%s", alpha_bin);

    for(i = 0; i < strlen(invalid); i++) {
        if(strchr(alpha_bin, invalid[i]) != NULL) {
            puts("invalid input");
            exit(0);
        }
    }

    (*(void  (*)()) alpha_bin)();

    return 0;
}