MOD = 10 ** 9 + 7

h, w = map(int, input().split())
S = [input() for _ in range(h)]

if S[0][0] != S[-1][-1]:
    print(0)
    exit()

dp = {(0, 0, h - 1, w - 1): 1}
directions = [(1, 0, -1, 0), (0, 1, -1, 0), (1, 0, 0, -1), (0, 1, 0, -1)]

for _ in range((h + w) // 2 - 1):
    ndp = {}
    for (i1, j1, i2, j2), v in dp.items():
        for di1, dj1, di2, dj2 in directions:
            ni1 = i1 + di1
            nj1 = j1 + dj1
            ni2 = i2 + di2
            nj2 = j2 + dj2
            if ni1 == h or nj1 == w or ni2 == -1 or nj2 == -1:
                continue
            if S[ni1][nj1] == S[ni2][nj2]:
                tmp = (ni1, nj1, ni2, nj2)
                ndp[tmp] = ndp.get(tmp, 0) + v
                ndp[tmp] %= MOD
    dp = ndp

ans = 0
for (i1, j1, i2, j2), v in dp.items():
    if abs(i1 - i2) + abs(j1 - j2) <= 1:
        ans += v
        ans %= MOD
print(ans)