Compilare: user.cpp: In function ‘void go(std::vector<std::pair<int, int> >&, std::vector<std::pair<int, int> >&)’: user.cpp:33:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k1 < a.size() && k2 < b.size()) { ^ user.cpp:33:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k1 < a.size() && k2 < b.size()) { ^ user.cpp:40:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k1 < a.size()) ^ user.cpp:42:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k2 < b.size()) ^ user.cpp: In function ‘int main()’: user.cpp:95:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < elem.size() - 1; ++i) ^ user.cpp:96:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = i + 1; j < elem.size(); ++j) ^ user.cpp:98:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < elem.size(); ++i) ^