Compilare: user.cpp: In function ‘int main()’: user.cpp:8:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mafia.in", "r", stdin); ^ user.cpp:9:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mafia.out", "w", stdout); ^ user.cpp:16:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld %lld %lld", &n, &m, &x); ^ user.cpp:18:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &u); ^ user.cpp:12:15: warning: ‘xx’ may be used uninitialized in this function [-Wmaybe-uninitialized] long long i, xx, u, a, b; ^