#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define mp make_pair
#define pb push_back
#define vll vector<ll>
#define endl "\n"
#define pll pair<ll,ll>
#define all(x) (x).begin() , (x).end()
#define f first
#define s second
#define pr(x) cout<<x<<endl;
#define pr2(x,y) cout<<x<<" "<<y<<endl;
#define pr3(x,y,z) cout<<x<<" "<<y<<endl;
#define prv(v) for(auto x:v) cout<<x<<" ";
#define ffs fflush(stdout);
#define int ll
using namespace std;
const ll N =(2e5+5);
ll MOD = 1e9+7;
const ll INF = LLONG_MAX;
const ll LOG = 29;
#define PI 3.141592653589793238
double circumference(double r)
{
double cir = 2.0;
cir*=PI;
cir*=r;
return cir;
}
ll m;
long long binpow(long long a, long long b) {
a%=MOD;
long long res = 1;
while (b > 0) {
if (b & 1)
res = (res * a)%MOD;
a = (a * a)%MOD;
b >>= 1;
}
res%=MOD;
return res;
}
int fac[N];
int power(int x, int y, int p)
{
int res = 1; // Initialize result
x = x % p; // Update x if it is more than or
// equal to p
while (y > 0)
{
// If y is odd, multiply x with result
if (y & 1)
res = (res*x) % p;
// y must be even now
y = y>>1; // y = y/2
x = (x*x) % p;
}
return res;
}
// Returns n^(-1) mod p
int modInverse(int n, int p)
{
return power(n, p-2, p);
}
// Returns nCr % p using Fermat's little
// theorem.
void comp(){
fac[0] = 1;
for (int i=1 ; i<N; i++)
fac[i] = fac[i-1]*i%MOD;
}
int nCrModPFermat(int n, int r, int p)
{
// Base case
if (r==0)
return 1;
// Fill factorial array so that we
// can find all factorial of r, n
// and n-r
return (fac[n]* modInverse(fac[r], p) % p *
modInverse(fac[n-r], p) % p) % p;
}
void solve(){
comp();
ll n,k;
cin>>n>>k;
ll ans = 0;
ll gg[k+1];
for(ll j = 0;j<=k;j++){
gg[j] = nCrModPFermat(n+1,j,MOD);
}
for(ll j = 0;j<=k;j++){
// cout<<gg[j]<<endl;
ll xd=1;
xd = (xd * binpow(k-j,n))%MOD;
if(xd<0)xd+=MOD;
xd = (xd * gg[j])%MOD;
if(xd<0)xd+=MOD;
if(j&1)
ans = (ans - xd)%MOD;
else
ans=(ans + xd)%MOD;
if(ans<0)ans+=MOD;
}
cout<<ans<<endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(NULL);
ll t=1;
while(t--){
solve();
}
}//42364286 418930126
// (3,2)
// (0,0) -> (-1,0) -> (-1,2) -> (3,2)
