Compilare: user.cpp: In function ‘void prefix()’: user.cpp:19:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 1; j < s.size();) ^ user.cpp: In function ‘void solve()’: user.cpp:38:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < S.size()) ^ user.cpp:43:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (j == s.size()) V.push_back(i - j); ^