#include <bits/stdc++.h>

#include <atcoder/modint>
using namespace std;

using Mint = atcoder::modint1000000007;

int main()
{
    int H, W;
    cin >> H >> W;
    vector<string> V(H);
    for (auto &x : V)
        cin >> x;

    vector<vector<Mint>> D(H, vector<Mint>(H));
    D[0][H - 1] = V[0][0] == V[H-1][W-1];

    for (int s = 0; s < (H + W - 2)/2; s++)
    {
        vector<vector<Mint>> E(H, vector<Mint>(H));
        for (int i = 0; i < H; i++)
            for (int j = 0; j < H; j++)
                if (D[i][j].val())
                {
                    int ux = i, uy = s - i, vx = j, vy = (H + W - 2 - s) - j;
                    if(ux != H-1 && vx != 0 && V[ux+1][uy] == V[vx-1][vy])
                        E[ux+1][vx-1] += D[i][j];
                    if(ux != H-1 && vy != 0 && V[ux+1][uy] == V[vx][vy-1])
                        E[ux+1][vx] += D[i][j];
                    if(uy != W-1 && vx != 0 && V[ux][uy+1] == V[vx-1][vy])
                        E[ux][vx-1] += D[i][j];
                    if(uy != W-1 && vy != 0 && V[ux][uy+1] == V[vx][vy-1])
                        E[ux][vx] += D[i][j];
                }
        D = E;
    }
    Mint ans = 0;
    for(int i=0; i<H; i++)
        ans += D[i][i];
    if(H%2 != W%2)
        for(int i=0; i<H-1; i++)
            ans += D[i][i+1];
    cout << ans.val() << endl;
}