H,W=map(int,input().split())
L=list()
for i in range(H):
  S=input()
  L.append(S)
mod=10**9+7
dp=dict()
for k in range(((H+W)//2)-1,-1,-1):
  #k:距離
  for i in range(k+1):
    for j in range(k+1):
      if 0<=H-1-j<H and 0<=W-1-(k-j)<W:
        if L[i][k-i]==L[H-1-j][W-1-(k-j)]:
          a=i
          b=k-i
          c=H-1-j
          d=W-1-(k-j)
          if not (a<=c and b<=d):
              dp[(a,b,c,d)]=0
              continue
          if k==((H+W)//2)-1:
            dp[(i,k-i,H-1-j,W-1-(k-j))]=1
          else:
            dp[(a,b,c,d)]=(dp[(a+1,b,c-1,d)]+dp[(a,b+1,c,d-1)]+dp[(a,b+1,c-1,d)]+dp[(a+1,b,c,d-1)])%mod
        else:
          dp[(i,k-i,H-1-j,W-1-(k-j))]=0
print(dp[(0,0,H-1,W-1)])