#include <iostream> using namespace std; typedef long long ll; const ll mod = 1000000007; ll fac[100002], invfac[100002], dp[100002]; ll pow(ll x, ll y) { ll ans = 1; ll k = 0; while((1LL << k ) <= y) { if((1LL<<k) & y) { ans *= x; ans %= mod; } k++; x *= x; x %= mod; } return ans; } ll comb(ll n, ll k) { ll ans = (fac[n] * invfac[k])%mod; ans = (ans * invfac[n-k])%mod; return ans; } int main() { ll n, k; cin >> n >> k; fac[0] = 1; for(int i=1;i<=100001;i++) fac[i] = (fac[i-1] * i)%mod; invfac[100001] = pow(fac[100001], mod - 2); for(int i=100000;i>=0;i--) invfac[i] = (invfac[i+1] * (i+1))%mod; ll ans = 0; dp[1] = 1; for(ll i=0;i<=k;i++) { if(i%2 == 0) ans += (pow(k-i, n) * comb(n+1, i))%mod; else ans -= (pow(k-i, n) * comb(n+1, i))%mod; ans %= mod; } ans += mod; ans %= mod; cout << ans; }