#include <iostream>
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 4e18+9, mod = 1e9+7;
vector<ll> fact, invfact;
ll binpow(ll a, ll b){
ll res = 1;
while(b > 0){
if(b&1){
res*=a;
res%=mod;
}
a*=a;
a%=mod;
b/=2;
}
return res;
}
ll modinv(ll x){
return binpow(x, mod-2);
}
void calcfact(int n){
fact.resize(n+1, 0);
invfact.resize(n+1, 0);
fact[0] = 1;
for(int i = 1; i <= n; i++){
fact[i] = fact[i-1]*i;
fact[i]%=mod;
}
invfact[n] = modinv(fact[n]);
for(int i = n-1; i >= 0; i--){
invfact[i] = invfact[i+1]*(i+1)%mod;
}
}
ll nCk(ll n, ll k){
if(k < 0 || k > n) return 0;
return fact[n]*(invfact[k]*invfact[n-k]%mod)%mod;
}
ll distributing_apples(ll n, ll m){ // number of people, apple
return nCk(m+n-1, n-1);
}
void solve(){
calcfact(2e5);
int n, k;
cin >> n >> k;
k--;
ll ans = 0;
for(int i = 0; i <= k; i++){
ans += (binpow(-1, i) * nCk(n+1, i) + mod) % mod * (binpow(k+1-i, n) + mod) % mod;
}
ans %= mod;
cout << ans;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
}
