#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007;
unordered_map<string, long long> m;
unordered_map<string, long long> mm;
inline void prop(string s, long long x){
//cout << s << " " << x << "\n";
if(x == 0) return;
for(char c = 'a';c <= 'z';c++){
//cout << s+c << " " << c+s << "\n";
string a = s + c;
string b = c + s;
long long res = mm[a];
res += x;
if(res >= mod) res -= mod;
mm[a] = res;
if(a != b){
res = mm[b];
res += x;
if(res >= mod) res -= mod;
mm[b] = res;
}
}
}
int main(){
//freopen("i.txt","r",stdin);
ios_base::sync_with_stdio(false);
cin.tie(0);
int n, k; cin >> n >> k;
if(n == 1){
cout << k;
return 0;
}
for(int j = 0;j < k;j++){
string s; cin >> s;
prop(s, 1);
}
for(int i = 2;i <= n-1;i++){
swap(m, mm);
mm.clear();
for(int j = 0;j < k;j++){
string s; cin >> s;
prop(s, m[s]);
}
}
long long ans = 0;
for(int j = 0;j < k;j++){
string s; cin >> s;
ans += mm[s];
//cout << mm[s] << "\n";
}
ans %= mod;
cout << ans;
}
