Compilare: user.cpp: In function ‘void solve(std::vector<int>&, std::vector<int>&)’: user.cpp:17:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < st.size() / 2; ++i) ^ user.cpp:28:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = st.size() / 2; i < st.size(); ++i) ^ user.cpp:43:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol_a.size(); ++i) ^ user.cpp:49:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sol_b.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:77:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < sir.size(); ++i) ^