Compilare: main.cpp: In function 'int main()': main.cpp:12:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; 3*i <= s.length(); i++) { ~~~~^~~~~~~~~~~~~ main.cpp:14:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j+2*i < s.length(); j++) ~~~~~~^~~~~~~~~~~~