Compilare: user.cpp: In function ‘int main()’: user.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<sol.size();i++) ^ user.cpp:61:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] else if(sol.size()<k) ^ user.cpp:40:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("salvare.in","r",stdin); ^ user.cpp:41:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("salvare.out","w",stdout); ^ user.cpp:42:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&k); ^ user.cpp:46:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] v[y].push_back(x); ^