MOD = 10**9 + 7

H, W = map(int, input().split())
grid = [input().strip() for _ in range(H)]

L = H + W - 1
P = L // 2

dp = [[0] * (W + 1) for _ in range(H + 1)]
dp[1][1] = 1 if grid[0][0] == grid[H-1][W-1] else 0

for i in range(1, H + 1):
    for j in range(1, W + 1):
        if i == 1 and j == 1:
            continue
        k = i + j - 2
        if k < P:
            mirror_i = H - i + 1
            mirror_j = W - j + 1
            if 1 <= mirror_i <= H and 1 <= mirror_j <= W:
                if grid[i-1][j-1] != grid[mirror_i-1][mirror_j-1]:
                    dp[i][j] = 0
                else:
                    dp[i][j] = (dp[i-1][j] + dp[i][j-1]) % MOD
            else:
                dp[i][j] = 0
        else:
            dp[i][j] = (dp[i-1][j] + dp[i][j-1]) % MOD

print(dp[H][W] % MOD)