#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
using namespace std;
using vi = vector<int>;
using vvi = vector<vi>;
using ll = long long;
const ll mod = 1'000'000'007;
int ad(ll a, ll b)
{
return (a+b)%mod;
}
int mul(ll a, ll b)
{
return (a*b)%mod;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int n, k;
cin >> n >> k;
string s[n];
vi val{0};
for(int i = 0; i < n; i++)
{
cin >> s[i];
sort(s[i].begin(), s[i].end());
}
sort(s, s+n);
for(int i = 0; i < n; i++)
{
if(i == 0 || s[i] != s[i-1]) val.push_back(1);
else val.back()++;
}
int ch[1+n][1+n];
for(int i = 0; i <= n; i++)
{
ch[i][0] = ch[i][i] = 1;
for(int j = 1; j < i; j++)
ch[i][j] = ch[i-1][j] + ch[i-1][j-1];
}
int z = int(val.size())-1;
vvi dp(1+z, vi(1+k, 0));
dp[0][0] = 1;
for(int i = 1; i <= z; i++)
{
for(int j = 0; j <= k; j++)
{
for(int c = 0; j - (c*(c-1)/2) >= 0 && c <= val[i]; c++)
{
dp[i][j] = ad(dp[i][j], mul(ch[val[i]][c], dp[i-1][j - (c*(c-1))/2]));
}
}
}
cout << dp[z][k] << '\n';
}
