Compilare: user.cpp: In function ‘void topsort(int)’: user.cpp:23:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[head].size(); i++) ^ user.cpp: In function ‘void dfs(int)’: user.cpp:31:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<vv[head].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:49:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j=0; j<v[i].size(); j++) ^