Compilare: user.cpp: In function ‘int main(int, const char**)’: user.cpp:41:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "online.in" , "r", stdin ); ^ user.cpp:42:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen( "online.out", "w", stdout ); ^ user.cpp:44:48: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int n, m, ans = 0; scanf( "%d %d", &n, &m ); ^ user.cpp:47:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int x, y, z; scanf( "%d %d %d", &x, &y, &z ); ^ user.cpp:70:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int k; scanf( "%d", &k ); printf( "%d\n", ans ); ^ user.cpp:73:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] int x, y, z; scanf( "%d %d %d", &x, &y, &z ); ^