Compilare: user.cpp: In function ‘int main()’: user.cpp:20:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while( l.empty() == 0 && l.size() + n - i -1 >= m && l.top() < sol[i]) ^ user.cpp:22:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if( l.size() < m) ^ user.cpp:10:10: warning: unused variable ‘x’ [-Wunused-variable] char x; ^ user.cpp:11:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("trompeta.in", "r", stdin); ^ user.cpp:12:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("trompeta.out", "w", stdout); ^ user.cpp:13:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d ", &n, &m); ^ user.cpp:16:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &sol[i]); ^