Compilare: main.cpp: In function 'void fb(int)': main.cpp:13:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<v[x].size();i++) ~^~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:51:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<v[x].size(); i++) ~^~~~~~~~~~~~