Compilare: user.cpp: In function ‘int main()’: user.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1; i<v.size(); i++) { ^ user.cpp:37:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<sol.size(); i++) g<<sol[i].first<<" "<<sol[i].second<<" "; ^