H,W = map(int,input().split())
S = [input() for _ in range(H)]
P = 10 ** 9 + 7

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

base = 10
mask = (1 << base) - 1
def pack(a,b,c,d):
    return (a << 30) + (b << 20) + (c << 10) + d
def unpack(x):
    d = x & mask
    x >>= base
    c = x & mask
    x >>= base
    b = x & mask
    a = x >> base
    return (a,b,c,d)
from collections import defaultdict
d = defaultdict(int)
d[pack(0,0,H - 1,W - 1)] = 1
ans = 0
u = H + W - 2
if u % 2 == 0:
    for _ in range(u // 2):
        nx = defaultdict(int)
        for x in d:
            h,w,hh,ww = unpack(x)
            for i,j in [(1,0),(0,1)]:
                for k,l in [(-1,0),(0,-1)]:
                    if h + i < H and w + j < W and hh + k >= 0 and ww + l >= 0:
                        if S[h + i][w + j] == S[hh + k][ww + l]:
                            nx[pack(h + i,w + j,hh + k,ww + l)] += d[pack(h,w,hh,ww)]
                            nx[pack(h + i,w + j,hh + k,ww + l)] %= P
        d = nx
    for u in d:
        h,w,hh,ww = unpack(u)
        if h == hh and w == ww:
            ans += d[u]
            ans %= P
    print(ans)
else:
    for _ in range(u // 2 + 1):
        nx = defaultdict(int)
        if _ < u // 2:
            for x in d:
                h,w,hh,ww = unpack(x)
                for i,j in [(1,0),(0,1)]:
                    for k,l in [(-1,0),(0,-1)]:
                        if h + i < H and w + j < W and hh + k >= 0 and ww + l >= 0:
                            if S[h + i][w + j] == S[hh + k][ww + l]:
                                nx[pack(h + i,w + j,hh + k,ww + l)] += d[x]
                                nx[pack(h + i,w + j,hh + k,ww + l)] %= P
        else:
            for x in d:
                h,w,hh,ww = unpack(x)
                for i,j in [(1,0),(0,1)]:
                    for k,l in [(-1,0),(0,-1)]:
                        if h + i < H and w + j < W and hh + k >= 0 and ww + l >= 0:
                            if S[h + i][w + j] == S[hh + k][ww + l]:
                                if h + i == hh and w + j == ww and hh + k == h and ww + l == w:
                                    ans += d[x]
                                    ans %= P
        d = nx
    print(ans)