Compilare: main.cpp: In function 'int main()': main.cpp:13:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i*3<=s.size();i++) ~~~^~~~~~~~~~ main.cpp:16:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0;j+2*i<s.size();j++) ~~~~~^~~~~~~~~