Compilare: main.cpp: In function 'int main()': main.cpp:10:50: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] #define FL(nm) do { freopen(nm ".in", "r", stdin); freopen(nm ".out", "w", stdout); } while (false) ^ main.cpp:28:5: note: in expansion of macro 'FL' FL("disjoint"); ^~ main.cpp:10:83: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] #define FL(nm) do { freopen(nm ".in", "r", stdin); freopen(nm ".out", "w", stdout); } while (false) ^ main.cpp:28:5: note: in expansion of macro 'FL' FL("disjoint"); ^~ main.cpp:31:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ main.cpp:39:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &o, &i, &j); ^