Compilare: main.cpp: In function 'void drum(int)': main.cpp:23:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<graf[a].size(); i++) ~^~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<graf[a].size(); i++) ~^~~~~~~~~~~~~~~