#include<bits/stdc++.h>
using namespace std;
template <int MOD_>
struct modnum {
static constexpr int MOD = MOD_;
static_assert(MOD_ > 0, "MOD must be positive");
private:
using ll = long long;
int v;
static int minv(int a, int m) {
a %= m;
assert(a);
return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
}
public:
modnum() : v(0) {}
modnum(ll v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
explicit operator int() const { return v; }
friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
friend std::istream& operator >> (std::istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }
friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }
modnum inv() const {
modnum res;
res.v = minv(v, MOD);
return res;
}
modnum neg() const {
modnum res;
res.v = v ? MOD-v : 0;
return res;
}
modnum operator- () const {
return neg();
}
modnum operator+ () const {
return modnum(*this);
}
modnum& operator ++ () {
v ++;
if (v == MOD) v = 0;
return *this;
}
modnum& operator -- () {
if (v == 0) v = MOD;
v --;
return *this;
}
modnum& operator += (const modnum& o) {
v += o.v;
if (v >= MOD) v -= MOD;
return *this;
}
modnum& operator -= (const modnum& o) {
v -= o.v;
if (v < 0) v += MOD;
return *this;
}
modnum& operator *= (const modnum& o) {
v = int(ll(v) * ll(o.v) % MOD);
return *this;
}
modnum& operator /= (const modnum& o) {
return *this *= o.inv();
}
friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};
using num = modnum<int(1e9) + 7>;
num powmod(num a, int b) {
num r = 1;
while (b) {
if (b & 1) {
r *= a;
}
a *= a;
b /= 2;
}
return r;
}
const int MAXN = 1.1e5;
int N, K;
num fact[MAXN];
num ifact[MAXN];
num choose(int n, int r) {
return fact[n] * ifact[r] * ifact[n-r];
}
int main() {
fact[0] = 1;
for (int i = 1; i < MAXN; i++) {
fact[i] = fact[i-1] * i;
}
ifact[MAXN-1] = fact[MAXN-1].inv();
for (int i = MAXN-1; i >= 1; i--) {
ifact[i-1] = ifact[i] * i;
}
cin >> N >> K;
num ans = 0;
for (int c = 0; c < K; c++) {
num ways = choose(N+1, c) * powmod(K-c, N);
if (c % 2 == 0) {
ans += ways;
} else {
ans -= ways;
}
}
cout << ans << '\n';
return 0;
}
