import sys

# sys.setrecursionlimit(200005)
int1 = lambda x: int(x)-1
pDB = lambda *x: print(*x, end="\n", file=sys.stderr)
p2D = lambda x: print(*x, sep="\n", end="\n\n", file=sys.stderr)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]
def LI1(): return list(map(int1, sys.stdin.readline().split()))
def LLI1(rows_number): return [LI1() for _ in range(rows_number)]
def SI(): return sys.stdin.readline().rstrip()
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0)]
# dij = [(0, 1), (-1, 0), (0, -1), (1, 0), (1, 1), (1, -1), (-1, 1), (-1, -1)]
inf = (1 << 63)-1
# inf = (1 << 31)-1
md = 10**9+7
# md = 998244353

from collections import defaultdict

h, w = LI()
ss = [SI() for _ in range(h)]

if ss[0][0] != ss[h-1][w-1]:
    print(0)
    exit()

dij = [(0, 1, 0, -1), (1, 0, 0, -1), (0, 1, -1, 0), (1, 0, -1, 0)]

dp = defaultdict(int)
dp[0, 0, h-1, w-1] = 1
n = h+w-1
for _ in range((n-1)//2):
    ndp = defaultdict(int)
    for (i, j, u, v), pre in dp.items():
        for di, dj, du, dv in dij:
            ni, nj, nu, nv = i+di, j+dj, u+du, v+dv
            if not 0 <= ni < h: continue
            if not 0 <= nj < w: continue
            if not 0 <= nu < h: continue
            if not 0 <= nv < w: continue
            if ss[ni][nj] != ss[nu][nv]: continue
            ndp[ni, nj, nu, nv] += pre
            ndp[ni, nj, nu, nv] %= md
    dp = ndp
# pDB(dp)

ans = 0
mid = (n-1)//2
if n & 1:
    for i in range(h):
        j = mid-i
        if not 0 <= j < w: continue
        ans += dp[i, j, i, j]
        ans %= md
else:
    for i in range(h):
        j = mid-i
        if not 0 <= j < w: continue
        for u, v in [(i+1, j), (i, j+1)]:
            if 0 <= u < h and 0 <= v < w and ss[i][j] == ss[u][v]:
                ans += dp[i, j, u, v]
                ans %= md

print(ans)