Compilare: user.cpp: In function ‘void add(std::string, int)’: user.cpp:31:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:53:11: warning: statement has no effect [-Wunused-value] for (m; m > 0; --m) { ^ user.cpp:59:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (v[refe[nr]].s.size() < lmin) ^ user.cpp:40:33: warning: unused variable ‘d’ [-Wunused-variable] int n, m, i, t, nr, n1, n2, d, lmin, step, ans; ^