Compilare: user.cpp: In function ‘int main()’: user.cpp:25:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(!d.empty()&&d.size()>=k&&s[d.back()]<=s[d.front()-1]) ^ user.cpp:27:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(d.size()>=k&&s[d.back()]-s[d.front()-1]>mx) { ^