#include <bits/stdc++.h>
#define ff first
#define ss second
#define endl '\n'
using namespace std;
const long long INF = (long long) 1e18;
const int mod = (int) 1e9+7;
const int MAXN = (int) 1e5+5;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
int n, k;
int dp[MAXN];
ll fact[MAXN];
ll inv[MAXN];
ll bp(ll a, ll b){
ll res = 1;
while(b){
if(b % 2) res = (res * a) % mod;
a = (a * a) % mod;
b = b / 2;
}
return res;
}
ll comb(ll a, ll b){
return fact[a]*inv[b]%mod*inv[a - b]%mod;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);cout.tie(nullptr);
#ifdef Local
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/int.txt","r",stdin);
freopen("C:/Users/Admin/Desktop/Yazilim/C/IO/out.txt","w",stdout);
#endif
cin>>n>>k;
fact[0] = 1;
inv[0] = 1;
for(int i = 1; i <= n + 10; i++){
fact[i] = fact[i - 1]* i % mod;
inv[i] = bp(fact[i], mod - 2);
}
ll ans = 0;
for(int i = 0; i < k; i++){
ans += (i % 2 ? -1: 1)*(comb(n + 1, i)*bp((k - i), n)%mod);
ans += mod;
ans %= mod;
}
cout<<ans<<endl;
#ifdef Local
cout<<endl<<fixed<<setprecision(2)<<1000.0 * clock() / CLOCKS_PER_SEC<< " milliseconds ";
#endif
}
