Compilare: user.cpp: In function ‘int main()’: user.cpp:15:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<s.size();i++) ^ user.cpp:22:70: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(!x.empty() && x.top()<s[i]-'0' && x.size()+n-i>m) ^ user.cpp:24:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(x.size()<m) ^