Compilare: user.cpp: In function ‘std::pair<int, int> sumadiv(long long int)’: user.cpp:39:67: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; 1LL * prime[i] * prime[i] <= n && i < prime.size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:80:68: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; 1LL * prime[i] * prime[i] <= n && i < prime.size(); ++i) ^