Compilare: user.cpp: In function ‘void dell(line)’: user.cpp:46:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<S.size();i++) ~^~~~~~~~~ user.cpp:48:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (;i+1<S.size();i++) S[i] = S[i+1]; ~~~^~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:78:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<M[P[i].x].size();j++) ~^~~~~~~~~~~~~~~~~