Compilare: main.cpp: In function 'int main()': main.cpp:12:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<s.size();i++) ~^~~~~~~~~ main.cpp:17:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0;i<s.size();i++) ~^~~~~~~~~ main.cpp:19:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 1;3*j+i-1<s.size();j++) ~~~~~~~^~~~~~~~~