func_code_string: #include <bits/stdc++.h>   using namespace std;   bool isPrime(long long int n) {     if (n <= 1) return false;     if (n <= 3) return true;     if (n % 2 == 0 || n % 3 == 0) return false;     for (long long int i = 5; i * i <= n; i = i + 6)       if (n % i == 0 || n % (i + 2) == 0) return false;     return true;   }   vector<int> gr[50005];   int n, k;   bool vis[50005];   int lev[50005][505];   long long int dp[50005];   void dfs(int v) {     vis[v] = true;     lev[v][0] = 1;     for (auto ed : gr[v]) {       if (!vis[ed]) {         dfs(ed);         for (long long int i = 1; i < k + 1; i++) lev[v][i] += lev[ed][i - 1];       }     }   }   void solve(int v) {     vis[v] = true;     for (auto ed : gr[v]) {       if (!vis[ed]) {         solve(ed);         for (long long int i = 1; i < k; i++)           dp[v] += lev[ed][i - 1] * (lev[v][k - i] - lev[ed][k - i - 1]);       }     }     dp[v] /= 2;     dp[v] += lev[v][k];   }   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n >> k;     int a, b;     for (long long int i = 0; i < n - 1; i++) {       cin >> a >> b;       gr[a].push_back(b);       gr[b].push_back(a);     }     memset(lev, 0, sizeof(lev));     memset(vis, false, sizeof(vis));     dfs(1);     memset(vis, false, sizeof(vis));     memset(dp, 0, sizeof(dp));     solve(1);     long long int ans = 0;     for (long long int i = 1; i < n + 1; i++) ans += dp[i];     cout << ans;   }   