#include<bits/stdc++.h>
using namespace std;
#define X first
#define Y second
#define int long long
#define sz(a) (int)a.size()
const int mod = 1e9 + 7;
const int N = 2e3 + 100;
int cnk[N][N];
signed main()
{
// ifstream cin("input1.txt.4c");
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
for(int i = 0; i < N; i++)
{
for(int j = 0; j < N; j++)
{
cnk[i][j] = 0;
}
}
cnk[0][0] = 1;
for(int i = 1; i < N; i++)
{
cnk[i][0] = 1;
for(int j = 1; j < N; j++)
{
cnk[i][j] = (cnk[i - 1][j] + cnk[i - 1][j - 1]) % mod;
}
}
int n, k;
cin >> n >> k;
map<vector <int>, int> mp;
for(int i = 0; i < n; i++)
{
string s;
cin >> s;
vector <int> cnt(26, 0);
for(int j = 0; j < sz(s); j++)
{
cnt[s[j] - 'a']++;
}
mp[cnt]++;
}
vector <int> dp(k + 1, 0);
dp[0] = 1;
for(auto p : mp)
{
int t = p.Y;
for(int j = k; j >= 0; j--)
{
for(int f = t; f >= 1; f--)
{
int add = f * (f - 1) / 2;
// cout << dp[j] << " " << add << " " << cnk[t][f] << "\n";
if(add + j <= k)
{
dp[add + j] = (dp[add + j] + dp[j] * cnk[t][f]) % mod;
}
}
}
// cout << dp[k] << "\n";
}
cout << dp[k];
return 0;
}
