#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int mod=1e9+7;
int n,K,a[305],f[305][305],ff[305][305],h[305][305],v1[305],jc[305],ny[305];
int C(int x,int y){
	if(x<y||y<0||x<0)return 0;
	return 1ll*jc[x]*ny[y]%mod*ny[x-y]%mod;
}
int Power(int x,int y){
	if(y<0)return Power(Power(x,mod-2),-y);
	int r=1;
	while(y){
		if(y&1)r=1ll*r*x%mod;
		x=1ll*x*x%mod,y>>=1;
	}
	return r;
}
int main(){
	cin>>n>>K;
	ny[0]=jc[0]=1;
	for(int i=1;i<=n;i++)jc[i]=1ll*jc[i-1]*i%mod;
	ny[n]=Power(jc[n],mod-2);
	for(int i=n-1;i;i--)ny[i]=1ll*ny[i+1]*(i+1)%mod;
	for(int i=1,x;i<=n;i++)cin>>x,a[x]++;
	h[0][0]=1;
	for(int i=1;i<=n;i++)v1[i]=1ll*ny[i]*Power(i,i-2)%mod*i%mod;
	for(int i=1;i<=n;i++){
		for(int j=1;j<=i;j++){
			for(int k=1;k<=K;k++){
				h[i][j]=(h[i][j]+1ll*h[i-k][j-1]*v1[k])%mod;
			}
		}
	}
	for(int i=1;i<=n;i++)for(int j=1;j<=i;j++)h[i][j]=1ll*h[i][j]*jc[i]%mod*ny[j]%mod;
	for(int i=1;i<=n;i++)f[i][0]=1;
	int m=0;
	for(int i=1;i<=n;i++){
		if(!a[i])continue;
		m++;
		for(int j=1;j<=a[i];j++){
			for(int k=j;k<=n;k++){
				for(int l=j;l<=k;l++){
					ff[k][l]=(ff[k][l]+1ll*f[k][l-j]*h[a[i]][j]%mod*Power(k-j,j-1))%mod;
				}
			}
		}
		memcpy(f,ff,sizeof(f));
		memset(ff,0,sizeof(ff));
	}
	int ans=0;
	for(int i=1;i<=n;i++)ans=(ans+1ll*f[i][i]*Power(n,m-2))%mod;
	cout<<ans;
}