#include "bits/stdc++.h"
#define fi first
#define se second
constexpr int maxn = 2e3 + 5;
constexpr int inf = 2e9;
constexpr int mod = 1e9 + 7;
using namespace std;
using lint = long long;
using pii = pair<int, int>;
int n, k;
int knap[2][maxn];
int c[maxn][maxn];
map<string, int> mp;
int m;
int sz[maxn];
vector<pii> p[maxn];
void precalc() {
for(int i = 0; i <= n; i++)
c[i][0] = 1;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= i; j++)
c[i][j] = (c[i - 1][j] + c[i - 1][j - 1]) % mod;
m = mp.size();
for(int i = 1; i <= m; i++) {
sz[i] = mp.begin()->se;
mp.erase(mp.begin());
for(int j = 1; j <= sz[i]; j++)
p[i].push_back({c[sz[i]][j], c[j][2]});
}
}
void solve() {
knap[1][0] = 1;
for(int i = 1; i <= m; i++) {
for(int j = 0; j <= k; j++)
knap[0][j] = knap[1][j];
for(auto [num, cnt] : p[i])
for(int j = k - cnt; j >= 0; j--) {
knap[1][j + cnt] += 1ll * num * knap[0][j] % mod;
knap[1][j + cnt] %= mod;
}
}
}
signed main() {
#ifdef Local
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
cin >> n >> k;
for(int i = 1; i <= n; i++) {
string str;
cin >> str;
sort(str.begin(), str.end());
mp[str]++;
}
precalc();
solve();
cout << knap[1][k] << endl;
}
