Compilare: user.cpp: In function ‘int main()’: user.cpp:94:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker3.in", "r", stdin); ^ user.cpp:95:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker3.out", "w", stdout); ^ user.cpp:103:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:109:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^ cc1plus: warning: iteration 49u invokes undefined behavior [-Waggressive-loop-optimizations] user.cpp:132:5: note: containing loop for(j = 0; j <= 50; ++ j) ^