#include <bits/stdc++.h>
#pragma GCC optimize("O2")
#pragma GCC target("avx2,fma")
#define rep(i,l,r) for (int i = l; i < r; i++)
#define repr(i,r,l) for (int i = r; i >= l; i--)
#define X first
#define Y second
#define pb push_back
#define endl '\n'
#define debug(x) cerr << #x << " : " << x << endl;
using namespace std;
typedef long long ll;
typedef pair<int,int> pll;
const long long int N = 2e3+20,mod = 1e9+7,inf = 1e9,sq = 65;
inline int mkay(int a,int b){
if (a+b >= mod) return a+b-mod;
if (a+b < 0) return a+b+mod;
return a+b;
}
inline int poww(int n,ll k){
int c = 1;
while (k){
if (k&1) c = (1ll*c*n)%mod;
n = (1ll*n*n)%mod;
k >>= 1;
}
return c;
}
int c[N][N],par[N],siz[N],sz[N];
int cnt[N][30],dp[N][2];
int getpar(int v){
if (par[v] == v) return v;
return par[v] = getpar(par[v]);
}
void mg(int u,int v){
u = getpar(u);
v = getpar(v);
if (u == v) return;
par[u] = v;
sz[v] += sz[u];
sz[u] = 0;
}
int main(){
ios :: sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n,y;
cin >> n >> y;
rep(i,0,n+1){
c[0][i] = 1;
par[i] = i;
sz[i] = 1;
}
rep(i,1,n+1) rep(j,i,n+1) c[i][j] = mkay(c[i-1][j-1],c[i][j-1]);
rep(i,1,n+1){
string s;
cin >> s;
siz[i] = s.size();
rep(j,0,siz[i]) cnt[i][s[j]-'a']++;
rep(j,1,i){
if (siz[j] != siz[i] || getpar(i) == getpar(j)) continue;
bool f = 1;
rep(k,0,26){
if (cnt[i][k] != cnt[j][k]){
f = 0;
break;
}
}
if (f) mg(i,j);
}
}
vector<int> ve;
ve.reserve(2001);
rep(i,1,n+1) if (sz[i]) ve.pb(sz[i]);
bool f = 1;
dp[0][0] = 1;
for (int u : ve){
rep(i,0,y+1){
dp[i][f] = 0;
rep(j,0,u+1){
if (c[2][j] > i) break;
dp[i][f] = mkay(dp[i][f],1ll*dp[i-c[2][j]][!f]*c[j][u]%mod);
}
}
f = !f;
}
cout << dp[y][!f];
}
