import sys
input = sys.stdin.readline
H, W = map(int, input().split())
a = [list(input())[: -1] for _ in range(H)]
mod = 10 ** 9 + 7

if a[0][0] != a[-1][-1]:
  print(0)
  exit(0)

base = H * W
from collections import deque as dq
Q = dq([H * W - 1])

d1 = [1, 0]
d2 = [-1, 0]

dp = [0] * (H * H * W * W)
dp[H * W - 1] = 1
vis = [0] * (H * H * W * W)

while len(Q):
  t = Q.popleft()
  u = t // base
  v = t % base
  if vis[t]: continue
  vis[t] = 1

  i, j = u // W, u % W
  y, x = v // W, v % W

  for k in range(2):
    i2, j2 = i + d1[k], j + d1[~k]
    if not (i2 in range(H) and j2 in range(W)): continue
    u2 = i2 * W + j2
    for kk in range(2):
      y2, x2 = y + d2[kk], x + d2[~kk]
      if not (y2 in range(H) and x2 in range(W)): continue
      if a[i2][j2] != a[y2][x2]: continue
      v2 = y2 * W + x2

      dp[u2 * base + v2] += dp[t]
      dp[u2 * base + v2] %= mod
      Q.append(u2 * base + v2)
      #print((i, j), (y,x),(i2, j2),(y2,x2))

  #print((i, j), (y, x), len(Q))

res = 0
for i in range(H):
  for j in range(W):
    res += dp[(i * W + j) * base + i * W + j]
    res %= mod
for i in range(H):
  for j in range(W):
    for k in range(2):
      u, v = i + d1[k], j + d1[~k]
      if u in range(H) and v in range(W) and a[i][j] == a[u][v]:
        res += dp[(i * W + j) * base + u * W + v]
        res %= mod
print(res)