func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, leaf, po;   vector<int> v[100005];   int main() {     scanf( %d , &n);     for (int i = (2); i <= (n); i++) {       int a, b;       scanf( %d %d , &a, &b);       v[a].push_back(b);       v[b].push_back(a);     }     for (int i = (1); i <= (n); i++)       if (v[i].size() == 1) leaf++;     po = 1;     for (int i = (1); i <= (n - leaf); i++) po = (po + po) % 1000000007;     printf( %d n , (1LL * po * (n - leaf) + 2LL * po * leaf) % 1000000007);     return 0;   }   