Compilare: main.cpp: In function 'int main()': main.cpp:4:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("nperechi.in", "r", stdin); ^ main.cpp:5:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("nperechi.out", "w", stdout); ^ main.cpp:7:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &a, &b, &c, &d); ^