Language: C

Source code:

#include <stdio.h> int main() { char input[256]; printf("Enter flag to check: "); scanf("%s", input); if (strcmp(input, "f1rst_FLAG") == 0) { printf("Yes! Correct flag is %s\n", input); return 0; } printf("Wrong check!\n"); return 0; }

Compiled Linux binary: mc1
Compiled Windows binary: mc1.exe