Compilare: user.cpp: In function ‘void solve()’: user.cpp:37:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < x.size(); i++) ^ user.cpp:39:49: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int q = x[i], i = 0; i < a[q].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:53:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < d.size(); cout << d[i++] << ' '); ^