Compilare: user.cpp: In function ‘int main()’: user.cpp:12:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alee.in", "r", stdin); ^ user.cpp:13:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alee.out", "w", stdout); ^ user.cpp:15:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hd %hd", &n, &m); ^ user.cpp:18:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hd %hd\n", &xx, &yy); ^ user.cpp:21:49: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hd %hd %hd %hd", &x1, &y1, &x2, &y2); ^