#include <iostream>
using namespace std;

const long long MAX = 510000;
const long long MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (long long i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(long long n, long long k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

int main() {
    // 前処理
    long long N,M;
	long long  a,b,c;
	cin >> N >> M;

	COMinit();

    // 計算例
    a=COM(N, M);
	
	long long wk;
	wk=1;
	//printf("a=%lld\n",a);
	for(long long i=0;i<M;i++){
		wk*=(i+1)%MOD;
		wk%=MOD;
		//printf("b=%lld\n",wk);
	}
	b=wk%MOD;

	//printf("b=%lld\n",b);
	a=a*b%MOD;

	if(N==M){
		printf("%lld",a);
		return 0;	
	}
	wk=(N-M);
	for(long long i=0;i<M-1;i++){
		wk*=wk%MOD;
		wk%=MOD;
	}
	c=wk;

	printf("%lld",a*c%MOD);
}