Compilare: user.cpp: In function ‘int main()’: user.cpp:13:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ndap.in", "r", stdin); ^ user.cpp:14:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ndap.out", "w", stdout); ^ user.cpp:20:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i %i", &N, &M); ^ user.cpp:21:62: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(int i = 1; i <= M; ++ i) scanf("%i %i", &X[i], &Y[i]); ^