#include <bits/stdc++.h>
using namespace std;
long long mod = 1000000007;
unordered_map<string, long long> m;
unordered_map<string, long long> mm;
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";
mm[s+c] += x;
if(s + c != c + s) mm[c+s] += x;
while(mm[c+s] >= mod) mm[c+s] -= mod;
}
}
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];
}
ans %= mod;
cout << ans;
}
