#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100005;
template<int SZ> struct Combo {
int fac[SZ+1], ifac[SZ+1];
ll mul(ll a, ll b) { return a*b%MOD; }
ll po (ll b, ll p) { return !p?1:po(b*b%MOD,p/2)*(p&1?b:1)%MOD; }
ll inv (ll b) { return po(b,MOD-2); }
Combo() {
fac[0] = ifac[0] = 1;
FOR(i,1,SZ+1)
fac[i] = mul(i,fac[i-1]), ifac[i] = inv(fac[i]);
}
ll comb(ll a, ll b) {
if (a < b || b < 0) return 0;
return mul(mul(fac[a],ifac[b]),ifac[a-b]);
}
};
Combo<MX> C;
ll po (ll b, ll p) { return !p?1:po(b*b%MOD,p/2)*(p&1?b:1)%MOD; }
ll inv (ll b) { return po(b,MOD-2); }
int ad(int a, int b) { return (a+b)%MOD; }
int sub(int a, int b) { return (a-b+MOD)%MOD; }
int mul(int a, int b) { return (ll)a*b%MOD; }
int N,K;
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> K; K --;
ll ans = 0;
F0R(i,K+1) {
ll pro = mul(po(K+1-i,N),C.comb(N+1,i));
if (i&1) ans = sub(ans,pro);
else ans = ad(ans,pro);
// ans += (-1)^i*(K+1-i)^N*(N+1)Ci
}
cout << ans;
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
*/
