#include <bits/stdc++.h>
using namespace std;
const int MAX_N = 1e5;
const int MOD = 1e9 + 7;
int fact[MAX_N], invfact[MAX_N];
int comb( int n, int k ) {
return (long long)fact[n] * invfact[k] % MOD * invfact[n - k] % MOD;
}
int lgpow ( int a, int n ) {
if ( n == 0 )
return 1;
int p = lgpow( a, n / 2 );
p = (long long)p * p % MOD;
if ( n % 2 == 1 )
p = (long long)p * a % MOD;
return p;
}
int main() {
int n, k;
cin >> n >> k;
fact[0] = 1;
for ( int i = 1; i <= n + 1; i++ )
fact[i] = (long long)fact[i - 1] * i % MOD;
invfact[n + 1] = lgpow( fact[n + 1], MOD - 2 );
for ( int i = n; i >= 0; i-- )
invfact[i] = (long long)invfact[i + 1] * (i + 1) % MOD;
int ans = 0;
for ( int i = 0; i < k; i++ )
ans = (ans + (long long)comb( n + 1, i ) * lgpow( k - i, n ) * (i % 2 == 0 ? 1 : -1) + MOD) % MOD;
cout << ans;
return 0;
}
