from collections import Counter
from collections import defaultdict
mod = 10 ** 9 + 7
U = 201


H, W = map(int, input().split())
G = [input() for _ in range(H)]
if H == 1 and W == 1:
    print(1)
    exit()


def id(x, y, xx, yy):
    res = x
    res = res * U + y
    res = res * U + xx
    res = res * U + yy
    return res


def parse(m):
    m, yy = divmod(m, U)
    m, xx = divmod(m, U)
    x, y = divmod(m, U)
    return x, y, xx, yy


if G[0][0] != G[H-1][W-1]:
    print(0)
    exit()
dp = defaultdict(int)
dp[id(0, 0, H-1, W-1)] = 1
while True:
    update = False
    finish = False
    ndp = defaultdict(int)
    for k, v in dp.items():
        x, y, xx, yy = parse(k)
        for di, dj in [(0, 1), (1, 0)]:
            nx = x + di
            ny = y + dj
            if nx < 0 or nx >= H or ny < 0 or ny >= W:
                continue
            for ddi, ddj in [(0, -1), (-1, 0)]:
                nnx = xx + ddi
                nny = yy + ddj
                if nnx < 0 or nnx >= H or nny < 0 or nny >= W:
                    continue
                if G[nx][ny] != G[nnx][nny]:
                    continue
                if (nx + ny) >= (nnx + nny):
                    finish = True
                    if (H + W - 1) % 2 == 1 and (nx, ny) != (nnx, nny):
                        continue
                    if (H + W - 1) % 2 == 0 and ((x, y) != (nnx, nny) or (nx, ny) != (xx, yy)):
                        continue
                ndp[id(nx, ny, nnx, nny)] += v
                ndp[id(nx, ny, nnx, nny)] %= mod
                update = True
    dp = ndp
    if finish:
        break
    if not update:
        break

if not finish:
    print(0)
else:
    ans = 0
    for k, v in dp.items():
        ans += v
        ans %= mod
    print(ans)