Compilare: main.cpp: In function 'int main()': main.cpp:80:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < s.size() ; ++j) ~~^~~~~~~~~~ main.cpp:109:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < G2.size() && nr < n ; ++i) ~~^~~~~~~~~~~