#include <iostream>
#include <string>
#include <map>
#include <algorithm>
using namespace std;
typedef long long ll;
const int MAXM = 2003;
const int MAXK = 2003;
const int MOD = 1000000007;
int ADD(ll a, ll b){
return (a+b)%MOD;
}
int MUL(ll a, ll b){
return a*b%MOD;
}
int EXP(ll b, ll e){
if(e==0) return 1;
else if(e%2==1) return MUL(b, EXP(b, e-1));
else return EXP(MUL(b, b), e/2);
}
int DIV(ll a, ll b){
return MUL(a, EXP(b, MOD-2));
}
int fact[MAXM];
int FACT(ll n){
return fact[n];
}
int CHOOSE(ll n, ll k){
return DIV(FACT(n), MUL(FACT(k), FACT(n-k)));
}
int n,k,m;
map<string, int> anagrami;
int a[MAXM];
int dp[MAXM][MAXK];
int solve(int m, int k){
int& res = dp[m][k];
if(res == -1){
if(m == 0){
if(k == 0) res = 1;
else res = 0;
}else{
res = 0;
for(int i=0;i <= a[m-1] && k >= i*(i-1)/2;i++){
res = ADD(res, MUL(CHOOSE(a[m-1], i), solve(m-1, k-i*(i-1)/2)));
}
}
}
return res;
}
int main(){
fact[0] = 1;
for(int i=1;i<MAXM;i++) fact[i] = MUL(i, fact[i-1]);
for(int i=0;i<MAXM;i++) fill(dp[i], dp[i]+MAXK, -1);
cin >> n >> k;
for(int i=0;i<n;i++){
string s;
cin >> s;
sort(s.begin(), s.end());
anagrami[s]++;
}
m = 0;
for(auto i:anagrami){
a[m++] = i.second;
}
cout << solve(m, k) << endl;
}
