// https://oeis.org/A008292
#include <bits/stdc++.h>
using namespace std;
const int Nmax = (1 << 17);
const int Mod = 1e9 + 7;
int Fact[Nmax], IFact[Nmax];
int mul(int a, int b) {
return 1LL * a * b % Mod;
}
int pow(int a, int b) {
int res = 1;
while (b > 0) {
if (b & 1) res = mul(res, a);
a = mul(a, a);
b >>= 1;
}
return res;
}
int binom(int n, int k) {
if (n < k) return 0;
return mul(Fact[n], mul(IFact[k], IFact[n - k]));
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
Fact[0] = 1;
for (int i = 1; i < Nmax; i++) Fact[i] = mul(Fact[i - 1], i);
IFact[Nmax - 1] = pow(Fact[Nmax - 1], Mod - 2);
for (int i = Nmax - 2; i >= 0; i--) IFact[i] = mul(IFact[i + 1], i + 1);
int N, K; cin >> N >> K;
int answer = 0;
for (int i = 0; i <= K; i++) {
int coef = mul(pow(K - i, N), binom(N + 1, i)) % Mod;
if (i % 2 == 0) {
answer += coef;
if (answer >= Mod) answer -= Mod;
}
if (i % 2 == 1) {
answer -= coef;
if (answer < 0) answer += Mod;
}
}
cout << answer << "\n";
return 0;
}
