#include<bits/stdc++.h>
using namespace std;
#define ALL(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(n);i++)
#define debug(v) cout<<#v<<":";for(auto x:v){cout<<x<<' ';}cout<<endl;
#define INF 1000000000
#define mod 1000000007
using ll=long long;
const ll LINF=1001002003004005006ll;
int dx[]={1,0,-1,0};
int dy[]={0,1,0,-1};
// ll gcd(ll a,ll b){return b?gcd(b,a%b):a;}
template<class T>bool chmax(T &a,const T &b){if(a<b){a=b;return true;}return false;}
template<class T>bool chmin(T &a,const T &b){if(b<a){a=b;return true;}return false;}

const int MAX=510000;
long long fac[MAX],finv[MAX],inv[MAX];
void COMinit(){
    fac[0]=fac[1]=1;finv[0]=finv[1]=1;inv[1]=1;
    for(int i=2;i<MAX;i++){
        fac[i]=fac[i-1]*i%mod;
        inv[i]=mod-inv[mod%i]*(mod/i)%mod;
        finv[i]=finv[i-1]*inv[i]%mod;
    }
}
long long COM(int n,int k){
    if(n<k) return 0;
    if(n<0 or k<0) return 0;
    return fac[n]*(finv[k]*finv[n-k]%mod)%mod;
}
ll fact_mod(ll n) {
    ll ret=1; 
    for(ll i=2;i<=n;i++) ret=ret*(i%mod)%mod;
    return ret;
} 
ll pow_mod(ll x, ll n){
    if(n==0) return 1;
    ll ret=pow_mod((x*x) % mod, n/2);
    if(n&1) ret=(ret*x)%mod;
    return ret;
}
//O(r)
ll combination_mod(ll n, ll r) {
    if(r>n-r) r=n-r;
    if(r==0) return 1;
    ll a=1;
    for(ll i=0;i<r;i++) a=a*((n-i)%mod)%mod;
    ll b=pow_mod(fact_mod(r), mod-2);
    return (a%mod)*(b%mod)%mod;
}
ll inv_mod(ll n){
    return pow_mod(n,mod-2);
}



signed main(){
    cin.tie(0);
    ios::sync_with_stdio(0);
    
    COMinit();

    ll k,n;cin>>n>>k;
    ll ans=0;
    for(ll i=0;i<=k;i++){
        ll res=COM(k,i)*pow_mod(i,n)%mod;
        // cout<<res<<endl;
        if((k-i)%2) res=mod-res;
        ans+=res;
        ans%=mod;
    }
    cout<<ans<<endl;
    return 0;
}