1 //#pragma comment(linker, "/STACK:102400000, 102400000") 2 #include <algorithm> 3 #include <iostream> 4 #include <cstdlib> 5 #include <cstring> 6 #include <cstdio> 7 #include <vector> 8 #include <cmath> 9 #include <ctime>10 #include <list>11 #include <set>12 #include <map>13 using namespace std;14 typedef long long LL;15 typedef pair <int, int> P;16 const int N = 1e5 + 5;17 int dp[50005][505], n, m;18 vector <int> G[50005];19 20 void dfs1(int u, int p) {21     dp[u][0] = 1;22     for(int i = 0; i < G[u].size(); ++i) {23         int v = G[u][i];24         if(v == p) 25             continue;26         dfs1(v, u);27         for(int i = 1; i <= m; ++i) {28             dp[u][i] += dp[v][i - 1];29         }30     }31 }32 33 void dfs2(int u, int p) {34     for(int i = 0; i < G[u].size(); ++i) {35         int v = G[u][i];36         if(v == p)37             continue;38         for(int i = m; i >= 2; --i) {39             dp[v][i] += dp[u][i - 1] - dp[v][i - 2];40         }41         dp[v][1]++;42         dfs2(v, u);43     }44 }45 46 int main()47 {48     int u, v;49     while(~scanf("%d %d", &n, &m)) {50         for(int i = 1; i < n; ++i) {51             scanf("%d %d", &u, &v);52             G[u].push_back(v);53             G[v].push_back(u);54         }55         if(m == 1) {56             printf("%d\n", n - 1);57         } else {58             dfs1(1, -1);59             dfs2(1, -1);60             LL ans = 0;61             for(int i = 1; i <= n; ++i) {62                 ans += (LL)dp[i][m];63             }64             printf("%lld\n", ans / 2);65         }66     }67     return 0;68 }