Compilare: user.cpp: In function ‘void dell(line)’: user.cpp:45:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<S.size();i++) ~^~~~~~~~~ user.cpp:47:22: 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 UPline(int, int)’: user.cpp:59:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<S.size();i++){ ~^~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:89:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<M[P[i].x].size();j++) ~^~~~~~~~~~~~~~~~~ user.cpp:97:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<E[i].size();j++) ~^~~~~~~~~~~~ user.cpp:101:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<M[i].size();j++) if (M[i][j]!=-1 && UPline(i,M[i][j])%2) nr++; ~^~~~~~~~~~~~