#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int readint(){
int x=0,f=1; char ch=getchar();
while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
return x*f;
}
const int cys=1000000007;
int n,k;
ll fac[100005],inv[100005];
int mod(int x){return x>=cys?x-cys:x;}
ll qpow(ll x,ll p){
ll ret=1;
for(;p;p>>=1,x=x*x%cys) if(p&1) ret=ret*x%cys;
return ret;
}
int main(){
n=readint(); k=n-readint()+1;
fac[0]=inv[0]=1;
for(int i=1;i<=n+1;i++) fac[i]=fac[i-1]*i%cys,inv[i]=qpow(fac[i],cys-2);
ll ans=0;
for(int i=0;i<=k;i++) ans=mod(ans+((i&1)?cys-1:1)*qpow(k-i,n)%cys*fac[n+1]%cys*inv[i]%cys*inv[n-i+1]%cys);
printf("%lld\n",ans);
return 0;
}
