#include <bits/stdc++.h>
using namespace std;
#define endl '\n'
#define sz(x) (int)x.size()
#define dbg(x) cerr << #x << ": " << x << endl;
using ll = long long;
#define int ll
const int MOD = 1e9+7;
const int N = 2005;
int bpow(int a, int b){
int r = 1;
while(b){
if(b&1){
r = r * a % MOD;
}
a = a * a % MOD;
b /= 2;
}
return r;
}
int inv(int x){
return bpow(x, MOD-2);
}
int fact[N];
int invfact[N];
void init(){
fact[0] = 1;
invfact[0] = inv(fact[0]);
for(int i=1; i<N; ++i){
fact[i] = fact[i-1] * i % MOD;
invfact[i] = inv(fact[i]);
}
}
int nck(int n, int k){
if(k > n) return 0;
int res = fact[n] * invfact[n-k] % MOD * invfact[k] % MOD;
return res;
}
signed main(){
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
init();
int n, k;
cin >> n >> k;
vector<string> s(n);
vector<int> comp;
for(int i=0; i<n; ++i){
cin >> s[i];
sort(s[i].begin(), s[i].end());
}
sort(s.begin(), s.end());
int cur = 1;
for(int i=1; i<n; ++i){
if(s[i] != s[i-1]){
// new
comp.push_back(cur);
cur = 1;
} else {
cur++;
}
}
comp.push_back(cur);
int m = sz(comp);
vector<vector<int>> dp(m+1, vector<int>(k+1, 0));
dp[0][0] = 1;
for(int i=0; i<m; ++i){
for(int j=0; j<=k; ++j){
for(int tam=0; tam <= comp[i]; ++tam){
int tmp = nck(tam, 2);
if(j + tmp > k) break;
int &res = dp[i+1][j + tmp];
res = (res + (dp[i][j] * nck(comp[i], tam) % MOD)) % MOD;
}
}
}
cout << dp[m][k];
}
