mod=10**9+7
H,W=map(int,input().split())
S=[input() for i in range(H)]
if S[0][0]!=S[-1][-1]:
  print(0)
  exit()
N=H+W-2
DP=[[[0]*H for i in range(H)] for j in range(N+1)]
DP[0][0][H-1]=1
ANS=0
for i in range(N):
  for j in range(H):
    for k in range(H):
      x1,y1=j,i-j
      x2,y2=k,W-1-(i-(H-1-k))
      if y1<0 or y2<0 or y2>=W:
        continue
      if abs(x1-x2)+abs(y1-y2)<=1:
        ANS=(ANS+DP[i][j][k])%mod
      for l in range(2):
        for m in range(2):
          x3,y3=x1+l,y1+(l^1)
          x4,y4=x2-m,y2-(m^1)
          if H<=x3 or W<=y3 or x4<0 or y4<0:
            continue
          if S[x3][y3]==S[x4][y4]:
            DP[i+1][j+l][k-m]=(DP[i+1][j+l][k-m]+DP[i][j][k])%mod
print(ANS)