Compilare: user.cpp: In function ‘int main()’: user.cpp:16:67: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(s[i]-'0'>out.back()-'0'&&out.size()&&n-i-1>=m-out.size()) //cout<<"scot "<<out.back()<<'\n', ^ user.cpp:18:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(out.size()<m) out.push_back(s[i]);// cout<<"bag "<<out.back()<<'\n'; ^