from itertools import product
from functools import cache

MOD = 10**9 + 7
H, W = map(int, input().split())
S = []
for i in range(H):
    S.append(input())


@cache
def f(r1, c1, r2, c2) -> int:
    if r1 == r2 and c1 == c2:
        return 1

    if r1 == r2 and c1+1 == c2:
        return 1 if S[r1][c1] == S[r2][c2] else 0

    if r1+1 == r2 and c1 == c2:
        return 1 if S[r1][c1] == S[r2][c2] else 0

    if S[r1][c1] != S[r2][c2]:
        return 0

    res = 0
    for (dr1, dc1), (dr2, dc2) in product([(0, 1), (1, 0)], [(0, -1), (-1, 0)]):
        nr1 = r1 + dr1
        nc1 = c1 + dc1
        nr2 = r2 + dr2
        nc2 = c2 + dc2
        if nr1 > nr2: continue
        if nc1 > nc2: continue
        res += f(nr1, nc1, nr2, nc2)
        res %= MOD

    return res


ans = f(0, 0, H-1, W-1)
print(ans)