Compilare: user.cpp: In function ‘int main()’: user.cpp:31:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<a.size();i++){ ^ user.cpp:32:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<(a.size()-1) && a[i]==a[i+1]) ^ user.cpp:38:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<G[i].size();j++) { ^ user.cpp:39:27: warning: variable ‘pp’ set but not used [-Wunused-but-set-variable] pair<int,int> pp = G[i][j]; ^