mod=10**9+7
def ans(a,b,c,d):
  if (a,b,c,d) in D:
    return D[(a,b,c,d)]
  if not (0<=a<H and 0<=b<W and 0<=c<H and 0<=d<W):
    return 0
  if L[a][b]!=L[c][d]:
    return 0
  if (a,b)==(c,d):
    return 1
  if (a+1,b)==(c,d) or (a,b+1)==(c,d):
    return 1
  X=(ans(a+1,b,c-1,d)+ans(a,b+1,c,d-1)+ans(a,b+1,c-1,d)+ans(a+1,b,c,d-1))%mod
  D[(a,b,c,d)]=X
  return X
H,W=map(int,input().split())
L=list()
for i in range(H):
  S=input()
  L.append(S)
D=dict()
print(ans(0,0,H-1,W-1))