Compilare: main.cpp: In function 'int main()': main.cpp:63:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("manhattan.in", "r", stdin); ^ main.cpp:64:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("manhattan.out", "w", stdout); ^ main.cpp: In member function 'void zona::scan()': main.cpp:12:41: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &x, &y, &u, &v); ^