View Compilation Error

0_0_36423272_10802.cpp: In function 'void dfs_2(int, std::vector<int>::iterator)':
0_0_36423272_10802.cpp:25:35: error: could not convert 'son_f.std::vector<_Tp, _Alloc>::begin<long long int, std::allocator<long long int> >()' from 'std::vector<long long int>::iterator {aka __gnu_cxx::__normal_iterator<long long int*, std::vector<long long int> >}' to 'std::vector<int>::iterator {aka __gnu_cxx::__normal_iterator<int*, std::vector<int> >}'
             dfs_2(v, son_f.begin());
                                   ^