#include <bits/stdc++.h>
#define int long long
#define MOD 1000000007
using namespace std;

vector<vector<int>>v;
queue<int>q;
int f[100005];
signed main()
{
    int n, k, a, b, p=1, x, y, z;
    cin>>n>>k;
    v.resize(n+1);
    for(int i=1; i<=n-1; i++)
    {
        cin>>a>>b;
        v[a].push_back(b);
        v[b].push_back(a);
    }
    q.push(1);f[1]=1;
    while(!q.empty())
    {
        z=q.front();
        q.pop();
        if(v[z].size()<=1)
        continue;
        n=v[z].size();
        a=1;b=1;
        for(int i=1; i<=n; i++)
        a*=i;
        for(int i=1; i<=k-n; i++)
        b*=i;
        x=a/b;
        if(k!=n)
        b=b/(k-n);
        y=a/b;
        //cout<<z<<" "<<x<<" "<<y<<endl;
        if(a==1)
        p=(p*x)%MOD;
        else
        p=(p*y)%MOD;
        for(int i=0; i<v[z].size(); i++)
        {
            b=v[z][i];
            if(f[b]==0)
            {
                f[b]=1;
                q.push(b);
            }
        }
    }
    cout<<p;

    return 0;
}