#include<bits/stdc++.h>
#define ll long long
#define pll pair<ll, ll>
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define ld long double
#define sz(a) ((ll)(a).size())
using namespace std;
const ll maxn=100005, Mod=1e9+7;
ll po[maxn], inv[maxn];
ll C(ll k, ll n){return po[n]*inv[k]%Mod*inv[n-k]%Mod;}
ll binpow(ll a, ll k)
{
ll ans=1;
for (; k; a=a*a%Mod, k>>=1)
if (k&1) ans=ans*a%Mod;
return ans;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll n, k; cin >> n >> k;
for (ll i=0; i<maxn; i++)
po[i]=i?po[i-1]*i%Mod:1;
inv[maxn-1]=binpow(po[maxn-1], Mod-2);
for (ll i=maxn-2; i>=0; i--)
inv[i]=inv[i+1]*(i+1)%Mod;
ll ans=0;
for (ll i=0; i<k; i++)
ans+=(i&1?-1:1)*C(i, n+1)*binpow(k-i, n)%Mod;
cout << (ans%Mod+Mod)%Mod;
}
