#include <stdio.h>
const long long mod = 1000000007;
long long pow(long long a, long long p)
{
long long r = 1;
a %= mod;
p = (p % (mod - 1) + mod - 1) % (mod - 1);
while (p){
if (p & 1) r = r * a % mod;
a = a * a % mod;
p /= 2;
}
return r;
}
long long comb[3003][3003],sti[3003][3003],fact[3003],prv[3003],nxt[3003];
int cnt[11];
int main()
{
int N,L;
scanf ("%d %d",&N,&L);
comb[0][0] = fact[0] = 1;
for (int i=1;i<=L;i++){
comb[i][i] = comb[i][0] = 1;
for (int j=1;j<i;j++) comb[i][j] = (comb[i-1][j-1] + comb[i-1][j]) % mod;
fact[i] = fact[i-1] * i % mod;
}
for (int i=0;i<N;i++){
int d; scanf ("%d",&d); cnt[d]++;
}
prv[0] = 1;
for (int i=1;i<=L;i++) prv[i] = prv[i-1] * cnt[0] % mod;
for (int d=1;d<=10;d++) if (cnt[d]){
sti[0][0] = 1;
for (int i=1;i<=L;i++){
for (int j=1;j<=cnt[d];j++){
sti[i][j] = j * sti[i-1][j] % mod;
if (i >= d) sti[i][j] = (sti[i][j] + comb[i-1][d-1] * sti[i-d][j-1]) % mod;
}
}
for (int i=0;i<=L;i++) nxt[i] = 0;
for (int i=0;i<=L;i++) for (int j=cnt[d]*d;i+j<=L;j++) nxt[i+j] = (nxt[i+j] + prv[i] * sti[j][cnt[d]] % mod * comb[i+j][j]) % mod;
for (int i=0;i<=L;i++) prv[i] = nxt[i] * fact[cnt[d]] % mod;
}
printf ("%lld\n",prv[L]*pow(N,-L)%mod);
return 0;
}
