#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N,B;
ll mo=1000000007;
vector<int> V;

ll P[202020],Q[202020];
ll L[202020],R[202020];
const int NUM_=400001;
static ll fact[NUM_+1],factr[NUM_+1],inv[NUM_+1];

ll comb(ll N_, ll C_) {
	if(C_<0 || C_>N_) return 0;
	return factr[C_]*fact[N_]%mo*factr[N_-C_]%mo;
}

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>B;
	map<int,int> M;
	FOR(i,N) {
		cin>>x;
		M[x]++;
	}

	inv[1]=fact[0]=factr[0]=1;
	for (int i=2;i<=NUM_;++i) inv[i] = inv[mo % i] * (mo - mo / i) % mo;
	for (int i=1;i<=NUM_;++i) fact[i]=fact[i-1]*i%mo, factr[i]=factr[i-1]*inv[i]%mo;
	
	FORR(v,M) {
		V.push_back(v.second);
	}
	N=V.size();
	int S=0;
	R[N+1]=1;
	for(i=N-1;i>=0;i--) {
		S+=V[i];
		P[i]=comb(S-1,V[i]-1)*fact[V[i]]%mo;
		Q[i]=comb(S-1,V[i])*fact[V[i]]%mo;
		R[i+1]=R[i+2]*(P[i]*B%mo+Q[i])%mo;
	}
	ll ret=0;
	L[0]=1;
	FOR(i,N) {
		L[i+1]=L[i]*(P[i]*B%mo+Q[i])%mo;
		(ret+=L[i]*P[i]%mo*R[i+2])%=mo;
	}
	
	cout<<B*ret%mo<<endl;
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}