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)

from collections import deque as dq
Q = dq([(0, H * W - 1)])

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

dp = [[0] * (H * W) for _ in range(H * W)]
dp[0][-1] = 1
vis = [[0] * (H * W) for _ in range(H * W)]

while len(Q):
  u, v = Q.popleft()
  if vis[u][v]: continue
  vis[u][v] = 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][v2] += dp[u][v]
      dp[u2][v2] %= mod
      Q.append((u2, 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][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][u * W + v]
        res %= mod
print(res)