Compilare: user.cpp: In function ‘int main()’: user.cpp:43:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (S[node.second].size() < k) S[node.second].push_back(node.first); ^ user.cpp:47:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (S[it->first].size() < k) ^ user.cpp:53:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < S[n].size(); i ++) ^