Compilare: user.cpp: In function ‘std::vector<int> Zalgo(const string&)’: user.cpp:15:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < that.size(); ++i) { ^ user.cpp:19:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i + z[i] < that.size() and s[z[i]] == s[i + z[i]]) { ^ user.cpp: In function ‘int main()’: user.cpp:38:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = a.size()+1; i < s.size(); ++i) { ^ user.cpp:39:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (z[i] == a.size()) { ^