#include <algorithm>
#include <iostream>
#include <numeric>
#include <cassert>
#include <vector>
typedef long long llong;
const int MAXN = 100000 + 10;
const int MOD = 1e9 + 7;
int n, k;
int dp[MAXN];
int newDP[MAXN];
llong fact[MAXN];
llong ifact[MAXN];
llong power(llong num, int base)
{
if (base == 0) return 1;
if (base & 1) return (num * power(num, base - 1)) % MOD;
llong res = power(num, base / 2);
return (res * res) % MOD;
}
llong comb(int from, int choose)
{
llong res = 1;
res *= fact[from]; res %= MOD;
res *= ifact[choose]; res %= MOD;
res *= ifact[from - choose]; res %= MOD;
return res;
}
void solve()
{
fact[0] = ifact[0] = 1;
for (int i = 1 ; i <= n + 1 ; ++i)
{
fact[i] = (fact[i - 1] * i) % MOD;
ifact[i] = power(fact[i], MOD - 2);
}
k--;
llong sum = 0;
for (int i = 0 ; i <= k ; ++i)
{
if (i % 2 == 0) sum = (sum + comb(n + 1, i) * power(k + 1 - i, n)) % MOD;
else sum = (sum + MOD - (((comb(n + 1, i) * power(k + 1 - i, n))) % MOD)) % MOD;
}
std::cout << sum << '\n';
}
void input()
{
std::cin >> n >> k;
}
void fastIOI()
{
std::ios_base :: sync_with_stdio(0);
std::cout.tie(nullptr);
std::cin.tie(nullptr);
}
int main()
{
fastIOI();
input();
solve();
return 0;
}
