Compilare: main.cpp: In function 'int main()': main.cpp:48:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen (FIN, "r", stdin); ^ main.cpp:49:31: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen (FOU, "w", stdout); ^ main.cpp:51:42: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d %d %d", &N, &M, &I, &J); ^ main.cpp:53:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &x, &y); ^