Compilare: main.cpp: In function 'int main()': main.cpp:16:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) ~~^~~~~~~~~~ main.cpp:18:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < s.size(); ++i) { ~~^~~~~~~~~~ main.cpp:29:16: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (phi[i] == s1.size() - 1) { ~~~~~~~^~~~~~~~~~~~~~~~