#include <iostream>
#include <vector>
#include <cmath>
#include <map>
#include <set>
#include <iomanip>
#include <queue>
#include <algorithm>
#include <numeric>
#include <deque>
#include <complex>
#include <cassert>

using namespace std;
using ll = long long;

const ll modc = 1e9+7;
class mint {
    ll x;
public:
    mint(ll x=0) : x((x%modc+modc)%modc) {}
    mint operator-() const {
      return mint(-x);
    }
    mint& operator+=(const mint& a) {
        if ((x += a.x) >= modc) x -= modc;
        return *this;
    }
    mint& operator-=(const mint& a) {
        if ((x += modc-a.x) >= modc) x -= modc;
        return *this;
    }
    mint& operator*=(const  mint& a) {
        (x *= a.x) %= modc;
        return *this;
    }
    mint operator+(const mint& a) const {
        mint res(*this);
        return res+=a;
    }
    mint operator-(const mint& a) const {
        mint res(*this);
        return res-=a;
    }
    mint operator*(const mint& a) const {
        mint res(*this);
        return res*=a;
    }
    mint pow(ll t) const {
        if (!t) return 1;
        mint a = pow(t>>1);
        a *= a;
        if (t&1) a *= *this;
        return a;
    }
    mint inv() const {
        return pow(modc-2);
    }
    mint& operator/=(const mint& a) {
        return (*this) *= a.inv();
    }
    mint operator/(const mint& a) const {
        mint res(*this);
        return res/=a;
    }

    friend ostream& operator<<(ostream& os, const mint& m){
        os << m.x;
        return os;
    }

    friend istream& operator>>(istream& ip, mint&m) {
        ip >> m.x;
        return ip;
    }
};

int main(){

    int H, W, l;
    cin >> H >> W;
    vector<vector<vector<mint>>> dp(H, vector(W, vector<mint>(H)));

    vector<string> S(H);
    for (int i=0; i<H; i++) cin >> S[i];

    for (int i=H-1; i>=0; i--){
        for (int j=W-1; j>=0; j--){
            for (int k=i; k<H; k++){
                l = H+W-2-i-j-k;
                if (l < j || W <= l) continue;
                if (k-i+l-j <= 1){
                    dp[i][j][k] = (S[i][j] == S[k][l]);
                    continue;
                }
                if (i+1<H && 0 <= k-1){
                    if (S[i+1][j] == S[k-1][l]) dp[i][j][k] += dp[i+1][j][k-1];
                }
                if (i+1<H && 0 <= l-1){
                    if (S[i+1][j] == S[k][l-1]) dp[i][j][k] += dp[i+1][j][k];
                }
                if (j+1<W && 0 <= k-1){
                    if (S[i][j+1] == S[k-1][l]) dp[i][j][k] += dp[i][j+1][k-1];
                }
                if (j+1<W && 0 <= l-1){
                    if (S[i][j+1] == S[k][l-1]) dp[i][j][k] += dp[i][j+1][k];
                }
            }
        }
    }

    cout << dp[0][0][H-1] << endl;
}