#include <bits/stdc++.h>
using namespace std;
const int N = 2e3 + 5, MOD = 1e9 + 7;
struct mint{
int val;
mint(long long a = 0) : val(a % MOD) {if(val < 0) val += MOD; }
mint(long long a, long long b) {*this += a, *this /= b; }
mint &operator += (const mint &b) {val += b.val; if(val >= MOD) val -= MOD; return *this; }
mint &operator -= (const mint &b) {val -= b.val; if(val < 0) val += MOD; return *this; }
mint &operator *= (const mint &b) {val = (1ll * val * b.val) % MOD; return *this; }
mint mexp(mint a, long long b){
mint c(1);
for(; b > 0; b /= 2, a *= a) if(b & 1) c *= a;
return c;
}
mint minv(const mint &a) {return mexp(a, MOD - 2); }
mint &operator /= (const mint &b) {return *this *= minv(b); }
friend mint operator + (mint a, const mint &b) {return a += b; }
friend mint operator - (mint a, const mint &b) {return a -= b; }
friend mint operator * (mint a, const mint &b) {return a *= b; }
friend mint operator / (mint a, const mint &b) {return a /= b; }
friend bool operator == (const mint &a, const mint &b) {return a.val == b.val; }
friend bool operator != (const mint &a, const mint &b) {return a.val != b.val; }
friend istream &operator >> (istream &is, mint &a) {long long b; is >> b; a = b; return is; }
friend ostream &operator << (ostream &os, const mint &a) {return os << a.val; }
};
int n, k, paircnt;
mint fact[N], invfact[N], knap[N], knap2[N];
vector<pair<int, mint>> v;
bool isknap[N], isknap2[N];
map<string, int> mp;
string str;
mint comb(int a, int b){
return fact[a] * (invfact[b] * invfact[a - b]);
}
void precalc(){
fact[0] = 1;
for(int i = 1; i < N; i++) fact[i] = fact[i - 1] * i;
invfact[N - 1] = mint(0).minv(fact[N - 1]);
for(int i = N - 2; i >= 0; i--) invfact[i] = invfact[i + 1] * (i + 1);
}
int main(){
ios_base::sync_with_stdio(false);cin.tie(NULL);
precalc();
cin >> n >> k;
for(int i = 0; i < n; i++){
cin >> str;
sort(str.begin(), str.end());
mp[str]++;
}
isknap[0] = true;
knap[0] = 1;
for(auto p : mp){
v.clear();
for(int i = 1; i <= p.second; i++){
paircnt = (i * (i - 1)) / 2;
if(paircnt < N) v.push_back({paircnt, comb(p.second, i)});
}
fill(knap2, knap2 + N, 0);
memset(isknap2, 0, sizeof(isknap2));
for(auto itm : v){
for(int i = N - 1; i >= itm.first; i--){
if(isknap[i - itm.first]){
isknap2[i] = true;
knap2[i] += knap[i - itm.first] * itm.second;
}
}
}
for(int i = 0; i < N; i++) isknap[i] |= isknap2[i], knap[i] += knap2[i];
}
cout << knap[k];
}
