#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cassert>
#include <iostream>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>
#include <set>
#include <map>
#include <bitset>
#include <fstream>
using namespace std;

#define repl(i,a,b) for(int i=(int)(a);i<(int)(b);i++)
#define rep(i,n) repl(i,0,n)
#define mp(a,b) make_pair(a,b)
#define pb(a) push_back(a)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
typedef long long ll;

#define INF 1000000000
#define MOD 1000000007

//long dp[100000];
long frac[100000];

// x^n mod
long mod_pow(long x, long n, long mod){
  long res=1;
  while(n>0){
    if(n&1) res=res*x%mod;
    x=x*x%mod;
    n>>=1;
  }
  return res;
}

/*
long comb(long n, long r){
    long p=1;
    for (long i=1; i<=r; i++) p=p*(n-i+1)/i;
    return p%MOD;
}
*/

long comb(long n, long m){
    long res =1;
    //for(long i=m+1;i<=n;i++) res = res*i%MOD;
    //long tmp=1;
    //for(long i=1; i<=n-m; i++) tmp = tmp*i%MOD; // (n-m)!
    res = frac[n]*mod_pow(frac[m], MOD-2, MOD)%MOD*mod_pow(frac[n-m], MOD-2, MOD)%MOD;
    return res;
}
/*
long calc(long n, long m){
    if(dp[m]!=-1) return dp[m];
    long res = mod_pow(m,n,MOD);
    for(long i=m-1; i>=1; i--){
        res = (res - comb(m,i)*calc(n, i) + MOD)%MOD;
    }
    return dp[m] = res;
}
*/

long calc(long n, long m){
    long res = 0;
    rep(i,m){
        res = (res+((i%2)?(-1):1)*comb(m,i)*mod_pow(m-i, n, MOD)+MOD)%MOD;
    }
    return res;
}

int main(){
    long n,m;
    cin>>n>>m;

    if(m>n){ cout<<0<<endl; return 0; }

    frac[0]=1;
    rep(i,m) frac[i+1]=(i+1)*frac[i]%MOD;

    /*fill(dp, dp+m+1, -1);
    dp[1]=1;*/
    cout<<calc(n,m)<<endl;

    return 0;
}