func_code_string: #include <bits/stdc++.h>   using namespace std;   int add(int _a, int _b) {     _a = (_a + 1000000007) % 1000000007;     _b = (_b + 1000000007) % 1000000007;     return (_a + _b) % 1000000007;   }   int mul(int _a, int _b) {     _a = (_a + 1000000007) % 1000000007;     _b = (_b + 1000000007) % 1000000007;     return ((long long int)((long long int)_a * (long long int)_b)) % 1000000007;   }   int n, k, sbtr[100010], sum[210], dif[100010][210],       sol = 0, fac[100010], inv[100010], h[100010][210], f[210][210];   vector<int> adj[100010];   void input() {     int i, j;     scanf( %d %d , &n, &k);     for (i = 0; i < n - 1; i++) {       int u, v;       scanf( %d %d , &u, &v), u--, v--;       adj[u].push_back(v), adj[v].push_back(u);     }   }   int bigMod(int v, int p) {     if (p == 0) {       return 1;     }     int ret = bigMod(v, p / 2);     if (p % 2 == 0) {       return mul(ret, ret);     } else {       return mul(ret, mul(ret, v));     }   }   void factorial() {     int i, j;     for (i = 1, fac[0] = inv[0] = 1; i < 100010 - 1; i++) {       fac[i] = mul(fac[i - 1], i);       inv[i] = mul(inv[i - 1], bigMod(i, 1000000007 - 2));     }   }   void H(int src) {     int sz = adj[src].size(), i, j, l, u, x;     for (i = sz - 1; i >= 0; i--) {       for (u = adj[src][i], j = 0; j <= min(k, sbtr[src] - 1); j++) {         if (i == sz - 1) {           if (j == 0) {             h[i][j] = add(1, dif[u][j]);           } else {             h[i][j] = add(dif[u][j], mul(j, dif[u][j - 1]));           }           continue;         }         for (l = 0, h[i][j] = 0; l <= min(sbtr[u], j); l++) {           x = mul(fac[j], mul(inv[l], inv[j - l]));           if (l == 0) {             x = mul(x, add(1, dif[u][0]));           } else {             x = mul(x, add(dif[u][l], mul(l, dif[u][l - 1])));           }           x = mul(x, h[i + 1][j - l]);           h[i][j] = add(h[i][j], x);         }       }     }   }   int F(int u, int v) {     int ret = 0;     if (v > u) {       return 0;     }     if (v == 0) {       return 0;     }     if (u == 1) {       return 1;     }     if (f[u][v] != -1) {       return f[u][v];     }     ret = add(mul(v, F(u - 1, v)), F(u - 1, v - 1));     return f[u][v] = ret;   }   bool cmp(int lhs, int rhs) { return sbtr[lhs] < sbtr[rhs]; }   void dfs(int src, int par) {     int i, j, idx = -1, mns, ret, u, x;     sbtr[src] = 1, ret = 0;     for (i = 0; i < adj[src].size(); i++) {       u = adj[src][i];       if (u == par) {         idx = i;         break;       }     }     if (idx != -1) {       adj[src].erase(adj[src].begin() + idx);     }     for (i = 0, dif[src][0] = 2, mns = 0; i < adj[src].size(); i++) {       u = adj[src][i];       dfs(u, src);       sbtr[src] += sbtr[u];       dif[src][0] = mul(dif[src][0], add(1, dif[u][0]));     }     sort(adj[src].begin(), adj[src].end(), cmp);     dif[src][0] = add(dif[src][0], -1);     for (j = 0; j <= k; j++) {       for (i = 0, sum[j] = 0; i < adj[src].size(); i++) {         int u = adj[src][i];         sum[j] = add(sum[j], dif[u][j]);       }     }     H(src);     for (i = 1; i <= min(k, sbtr[src] - 1); i++) {       u = adj[src][0];       x = mul(2, h[0][i]);       dif[src][i] = x;       x = add(x, -sum[i]);       x = add(x, -(mul(i, sum[i - 1])));       x = mul(x, F(k, i));       ret = add(ret, x);     }     sol = add(sol, ret);   }   void solve() {     int i, j;     memset(f, -1, sizeof(f));     factorial();     dfs(0, -1);     printf( %d , sol);     puts(  );   }   int main() {     input();     solve();   }   