Compilare: main.cpp: In function 'void dfs(int)': main.cpp:11:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<a[nod].size();i++) { ~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:32:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=1;j<a[i].size();j++) { ~^~~~~~~~~~~~