// "Say:He is the Most Merciful,We have believed in him and upon him we have relied" [67:29]
#include<bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
bool is(string a, string b){
char x = a.back();
a.pop_back();
if(a == b){
return 1;
}
a.push_back(x);
a.erase(a.begin());
if(a == b){
return 1;
}
return 0;
}
void add_self(int &a, int b){
a += b;
if(a >= mod){
a -= mod;
}
}
int main(){
int n, m; cin >> n >> m;
vector<vector<string>>v(n+1, vector<string>(m+1));
vector<vector<int>>dp(n+1, vector<int>(m+1));
for(int i=1;i<=n; i++){
for(int j=1; j<=m; j++){
cin >> v[i][j];
if(i == n){
dp[i][j] = 1;
}
}
}
for(int i=n-1; i>=1; i--){
for(int j=1; j<=m; j++){
for(int x=1; x<=m; x++){
if(is(v[i+1][x], v[i][j])){
add_self(dp[i][j], dp[i+1][x]);
}
}
}
}
int sum = 0;
for(int i=1; i<=m; i++){
add_self(sum, dp[1][i]);
}
cout << sum << "\n";
return 0;
}
