Compilare: main.cpp: In function 'int main()': main.cpp:11:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fof.in", "r", stdin); ^ main.cpp:12:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fof.out", "w", stdout); ^ main.cpp:13:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int n, m; scanf("%d %d", &n, &m); ^ main.cpp:15:35: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] int x, y; scanf("%d %d", &x, &y); ^