Compilare: user.cpp: In function ‘int main()’: user.cpp:7:39: 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); ^ user.cpp:8:41: 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); ^ user.cpp:9:54: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int A, B, C, D; scanf("%d%d%d%d", &A, &B, &C, &D); ^