#include <cstdio>
#include <cstdlib>
#include <cstring>

FILE *fin=fopen("colorare3.in","r");
FILE *fout=fopen("colorare3.out","w");

#define MODNR 1000000007

int c[100000];
int nrn[100000];

int comb(int ii, int jj)
{
    long long res=1;
    for (int i=jj; i>jj-ii; i--)
        res=(res*i)%MODNR;
    return res;
}

int main()
{
    int n,k;
    fscanf(fin,"%d %d",&n,&k);
    memset(nrn,0,sizeof(int)*n);
    for (int i=0; i<n-1; i++)
    {
        int x,y;
        fscanf(fin,"%d %d",&x,&y);
        x--;
        y--;
        nrn[x]++;
        nrn[y]++;
    }
    long long nr=1;
    for (int i=0; i<n; i++)
    {
        nr=(nr*(i?comb(nrn[i]-1,k-1):comb(nrn[i],k)))%MODNR;
    }
    fprintf(fout,"%lld",nr);
    fclose(fout);
    fclose(fin);
    return 0;
}