Compilare: user.cpp: In function ‘void solve()’: user.cpp:75:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j<=U.size();++j) { ^ user.cpp:76:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k < D.size() && (j>=U.size() || D[k].fs < U[j].fs)) { ^ user.cpp:76:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (k < D.size() && (j>=U.size() || D[k].fs < U[j].fs)) { ^ user.cpp:87:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j>=U.size()) { ^