Compilare: user.cpp: In function ‘long long unsigned int fact(long long unsigned int)’: user.cpp:8:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 2; i <= n; ++i) sol = (sol * i) % MODULO; ^ user.cpp: In function ‘int main()’: user.cpp:33:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == n.size() - 1) { ^ user.cpp:35:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < n.size(); ++i) { ^