#include<bits/stdc++.h>
typedef long long ll;
using namespace std;
int read()
{
	int ret=0;bool f=0;char c=getchar();
	while(c>'9'||c<'0')f|=(c=='-'),c=getchar();
	while(c>='0'&&c<='9')ret=(ret<<3)+(ret<<1)+(c^48),c=getchar();
	return f?-ret:ret;
}
const int maxn=305,mod=1e9+7;
int n,k;
int cnt[maxn],ccnt[maxn];
int qpow(int a,int b){if(b<0)a=qpow(a,mod-2),b=-b;int ret=1;for(;b;b>>=1,a=(ll)a*a%mod)if(b&1)ret=(ll)ret*a%mod;return ret;}
class mint
{
	public:
	int v;
	mint()=default;
	mint(int _v):v(_v){}
	mint&operator+=(const mint &rhs){v+=rhs.v;if(v>=mod)v-=mod;return *this;}
	mint&operator-=(const mint &rhs){v-=rhs.v;if(v<0)v+=mod;return *this;}
	mint&operator*=(const mint &rhs){v=(ll)v*rhs.v%mod;return *this;}
	mint&operator/=(const mint &rhs){v=(ll)v*rhs.inv().v%mod;return *this;}	
	mint inv()const{return qpow(v,mod-2);}
	friend mint operator +(const mint &lhs,const mint &rhs){return (mint)lhs+=rhs;}
	friend mint operator -(const mint &lhs,const mint &rhs){return (mint)lhs-=rhs;}
	friend mint operator *(const mint &lhs,const mint &rhs){return (mint)lhs*=rhs;}
	friend mint operator /(const mint &lhs,const mint &rhs){return (mint)lhs/=rhs;}
	mint pow(int c){return qpow(v,c);}
};
mint ans,fac[maxn],inv[maxn],ifac[maxn];
mint solve(int c)
{
	vector<mint>ret(c+1),f(c+1);
	for(int i=1;i<=min(k,c);i++)f[i]=(n-c)*ifac[i-1]*qpow(i,i-2);
	
	for(int i=0;i<c;i++)f[i]=f[i+1]*(i+1);f.resize(c);
	ret[0]=1;
	auto add=[&](int p,mint v)
	{
		for(int i=p;i<c;i++)
			ret[i+1]+=v*f[i-p]*inv[i+1];
	};
	add(0,1);
	for(int i=1;i<c;i++)
		add(i,ret[i]);
	return ret[c]*fac[c];
}
int main()
{
	n=read();k=read();
	for(int i=1;i<=n;i++)cnt[read()]++;
	for(int i=1;i<=n;i++)ccnt[cnt[i]]++;
	if(ccnt[n]){printf("%d\n",k<=n?mint(n).pow(n-2).v:0);return 0;}
	fac[0]=1;for(int i=1;i<=n;i++)fac[i]=fac[i-1]*i;
	ifac[n]=fac[n].inv();for(int i=n-1;i>=0;i--)ifac[i]=ifac[i+1]*(i+1);
	for(int i=1;i<=n;i++)inv[i]=ifac[i]*fac[i-1];
	ans=1;
	for(int i=1;i<=n;i++)
		if(ccnt[i])ans*=solve(i).pow(ccnt[i]);
	ans*=mint(n).pow(n-2);
	for(int i=1;i<=n;i++)ans/=n-cnt[i];
	printf("%d\n",ans.v);
	return 0;
}