Compilare: user.cpp: In function ‘void computepre(std::__cxx11::string)’: user.cpp:24:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < s.size()) { ^ user.cpp: In function ‘int main()’: user.cpp:45:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = s1.size(); i < s1.size() + s2.size() + 1; i++) { ^ user.cpp:46:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(pre[i] == s1.size()) { ^ user.cpp:54:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < sol.size(); i++) ^