#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MOD = 1e9+7;
const int MAXN = 2000;
vector<int> fact;
ll inv(ll a, ll b) {
ll res = 1;
while (b > 0) {
if (b % 2 == 1) {
res *= a;
res %= MOD;
}
b /= 2;
a *= a;
a %= MOD;
}
return res;
}
ll nCr(ll n, ll r) {
if (r == 0) return 1;
return fact[n]*inv((fact[r]*fact[n-r]) % MOD, MOD-2) % MOD;
}
int main() {
fact.resize(MAXN+1);
fact[0] = 1;
for (int i = 1; i <= MAXN; i++) fact[i] = (fact[i-1]*i) % MOD;
int n, k;
cin >> n >> k;
map<string, int> freq;
for (int i = 0; i < n; i++) {
string s;
cin >> s;
sort(s.begin(), s.end());
freq[s]++;
}
// dp[j] stores the number of subsets possible if there are exactly j similar pairs
vector<ll> dp(k+1);
dp[0] = 1;
for (auto x : freq) {
int f = x.second;
for (int j = k; j >= 0; j--) {
for (int p = 1; p <= f; p++) {
if (p*(p-1)/2 <= j) {
dp[j] += dp[j-(p*(p-1)/2)]*nCr(f, p) % MOD;
dp[j] %= MOD;
}
else break;
}
}
}
cout << dp[k] << '\n';
return 0;
}
