#include <iostream>

#include <cstdio>

#include <algorithm>

#include <cstring>

#define gc getchar()

#define ULL unsigned long long

#define LL long long

inline int read() {

    int x = ; char c = gc;

    while(c < '' || c > '') c = gc;

    while(c >= '' && c <= '') x = x *  + c - '', c = gc;

    return x;

}

const int N = 1e5 + , Mod = 1e9 + ;

int head[N], cnt;

struct Node {int u, v, nxt;} G[N << ];

int size[N], deep[N];

int n, k;

ULL fac[N];

inline void Add(int u, int v) {G[++ cnt].v = v; G[cnt].nxt = head[u]; head[u] = cnt;}

void Dfs(int u, int fa, int dep) {

    size[u] = , deep[u] = dep;

    for(int i = head[u]; ~ i; i = G[i].nxt) {

        int v = G[i].v;

        if(v == fa) continue;

        Dfs(v, u, dep + );

        size[u] += size[v];

    }

}

ULL Ksm(ULL a, ULL b) {

    ULL ret = ;

    while(b) {

        if(b & ) ret = (ret * a) % Mod;

        a = (a * a) % Mod;

        b >>= ;

    }

    return ret;

}

Node E[N];

inline ULL C(int n_, int m_) {

    if(m_ > n_) return ;

    ULL x = (fac[m_] * fac[n_ - m_]) % Mod;

    return (ULL) (fac[n_] * Ksm(x, Mod - )) % Mod;

}

int main() {

    n = read(), k = read();

    fac[] = fac[] = ;

    for(int i = ; i <= n; i ++) fac[i] = (fac[i - ] * i) % Mod;

    for(int i = ; i <= n; i ++) head[i] = -;

    for(int i = ; i < n; i ++) {

        int u = read(), v = read(); Add(u, v), Add(v, u);

        E[i].u = u, E[i].v = v;

    }

    Dfs(, , );

    LL a1 = C(n, k);

    LL Answer = ;

    for(int i = ; i < n; i ++) {

        int x = E[i].u, y = E[i].v;

        if(deep[x] < deep[y]) std:: swap(x, y);

        int siz1 = size[x], siz2 = n - siz1;

        LL  a2 = C(siz1, k), a3 = C(siz2, k);

        Answer = (Answer + (a1 - a2 - a3) % Mod) % Mod;

    }

    while(Answer < ) Answer += Mod;

    std:: cout << Answer;

    return ;

}