# include <bits/stdc++.h>
using namespace std;
const long long mod = 1e9 + 7;
const long long N = 1e5 + 2;
long long binpow(long long a, long long n){
long long res = 1;
while(n){
if(n & 1)
res = (res * a) % mod;
a = (a * a) % mod;
n >>= 1;
}
return res;
}
long long n, k, f[N], fi[N];
long long cnk(long long n, long long k){
return ((f[n] * fi[n - k]) % mod * fi[k]) % mod;
}
int main(){
f[0] = 1;
fi[0] = binpow(f[0], mod - 2);
for(long long i = 1; i < N; i ++){
f[i] = (f[i - 1] * i) % mod;
fi[i] = binpow(f[i], mod - 2);
}
cin >> n >> k;
long long ans = 0;
for(long long i = 0; i <= k; i ++){
if(i & 1){
ans -= (cnk(n + 1, i) * binpow(k - i, n)) % mod;
if(ans < 0) ans += mod;
} else {
ans += (cnk(n + 1, i) * binpow(k - i, n)) % mod;
if(ans > mod) ans -= mod;
}
}
cout << ans << endl;
}
