from collections import defaultdict
import sys
input = sys.stdin.readline

mod = 10**9 + 7
H, W = map(int, input().split())
S = [input().rstrip() for _ in range(H)]
if S[0][0] != S[H-1][W-1]:
    print(0)
    exit()
dp = {(0, 0, H-1, W-1): 1}
for k in range((H+W-1)//2):
    ndp = defaultdict(int)
    for (i, j, k, l), w in dp.items():
        w %= mod
        for di, dj in [(1, 0), (0, 1)]:
            ni, nj = i+di, j+dj
            if ni < 0 or H <= ni or nj < 0 or W <= nj:
                continue
            for dk, dl in [(-1, 0), (0, -1)]:
                nk, nl = k+dk, l+dl
                if nk < 0 or H <= nk or nl < 0 or W <= nl:
                    continue
                if S[ni][nj] == S[nk][nl]:
                    ndp[(ni, nj, nk, nl)] += w
    dp = ndp

ans = 0
if (H+W-1)%2:
    for (i, j, k, l), w in dp.items():
        if (i, j) == (k, l):
            ans = (ans + w) % mod
else:
    for (i, j, k, l), w in dp.items():
        if abs(i-k)+abs(j-l) == 1:
            ans = (ans + w) % mod
print(ans)