#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
const ll mod = 1e9 + 7;
ll fact[10000];
void precalc() {
fact[0] = 0;
fact[1] = 1;
for (int i = 2; i < 10000; i++) {
fact[i] = i * fact[i - 1];
fact[i] %= mod;
}
}
ll binpow(ll x, int p) {
if (p == 0)return 1;
if (p % 2 == 0) {
ll res = binpow(x, p / 2);
res *= res;
res %= mod;
return res;
} else {
return (x * binpow(x, p - 1)) % mod;
}
}
ll inv(ll x) {
return binpow(x, mod - 2);
}
ll C(ll a, ll b) {
if (a == b)return 1;
if (b == 0)return 1;
ll res = fact[a];
ll d = fact[b] * fact[a - b];
d %= mod;
res *= inv(d);
res %= mod;
return res;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
precalc();
int n, k;
cin >> n >> k;
map<string, int> mp;
for (int i = 0; i < n; i++) {
string s;
cin >> s;
sort(s.begin(), s.end());
mp[s]++;
}
vector<int> a;
for (auto& el: mp) {
a.push_back(el.second);
}
n = a.size();
vector<vector<ll>> dp(n + 1, vector<ll>(k + 1, 0));
dp[0][0] = 1;
for (int i = 1; i <= n; i++) {
vector<ll> b(a[i - 1] + 1, 0);
for (int t = 0; t <= a[i - 1]; t++) {
b[t] = C(a[i - 1], t);
b[t] %= mod;
}
for (int j = 0; j <= k; j++) {
for (int t = 0; t <= a[i - 1]; t++) {
int cntpairs = t * (t - 1) / 2;
if (cntpairs > j)continue;
dp[i][j] += b[t] * dp[i - 1][j - cntpairs];
dp[i][j] %= mod;
}
}
}
cout << dp[n][k] << endl;
}
