Compilare: main.cpp: In function 'int main()': main.cpp:25:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<s.size();++i) ~^~~~~~~~~ main.cpp:27:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int l=2;l<=s.size();++l) ~^~~~~~~~~~ main.cpp:28:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i+l-1<s.size();++i) ~~~~~^~~~~~~~~