#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> pll;
#define all(x) (x).begin(),(x).end()
#define X first
#define Y second
#define sep ' '
#define endl '\n'
#define debug(x) cerr << #x << ": " << x << endl;
const ll MAXN = 1e5 + 10;
const ll MOD = 1e9 + 7;
inline ll poww(ll a, ll b) {
ll ans = 1;
while (b) {
if (b & 1) ans = ans * a % MOD;
a = a * a % MOD;
b >>= 1;
}
return ans;
}
ll fact[MAXN], inv[MAXN];
inline ll C(ll k, ll n) {
if (k < 0 || k > n) return 0;
return fact[n] * inv[k] % MOD * inv[n - k] % MOD;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
fact[0] = inv[0] = 1;
for (int i = 1; i < MAXN; i++) {
fact[i] = fact[i - 1] * i % MOD;
inv[i] = poww(fact[i], MOD - 2);
}
ll ans = 0;
ll n, k;
cin >> n >> k;
for (int i = 0; i <= k; i++) {
ans = (ans + MOD + (i & 1 ? -1 : 1) * C(i, n + 1) * poww(k - i, n) % MOD) % MOD;
}
cout << ans << endl;
return 0;
}
