def main():
  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):
        a=i
        b=k-i
        c=H-1-j
        d=W-1-(k-j)
        if 0<=a<H and 0<=b<W and 0<=c<H and 0<=d<W:
          dp[(a,b,c,d)]=0
          if L[a][b]==L[c][d]:
            if not (a<=c and b<=d):
                dp[(a,b,c,d)]=0
                continue
            if k==((H+W)//2)-1:
              dp[(a,b,c,d)]=1
              continue
            else:
              if a!=H-1:
                if c!=0:
                  dp[(a,b,c,d)]+=dp[(a+1,b,c-1,d)]
                if d!=0:
                  dp[(a,b,c,d)]+=dp[(a+1,b,c,d-1)]
              if b!=W-1:
                if c!=0:
                  dp[(a,b,c,d)]+=dp[(a,b+1,c-1,d)]
                if d!=0:
                  dp[(a,b,c,d)]+=dp[(a,b+1,c,d-1)]
              dp[(a,b,c,d)]%=mod
          else:
            dp[(i,k-i,H-1-j,W-1-(k-j))]=0
  print(dp[(0,0,H-1,W-1)])
main()