from collections import defaultdict
mod=10**9+7

h,w=map(int,input().split())
s=[]
for i in range(h):
  s.append(list(input()))

dp=defaultdict(int)
if (h+w)%2==0:
  for i1 in range(h):
    j1=(h+w-2)//2-i1
    if 0<=j1<w:
      dp[(i1,j1,i1,j1)]=1
else:
  for i1 in range(h):
    j1=(h+w-3)//2-i1
    if 0<=j1<w:
      for i2,j2 in [(i1+1,j1),(i1,j1+1)]:
        if 0<=i2<h and 0<=j2<w and s[i1][j1]==s[i2][j2]:
          dp[(i1,j1,i2,j2)]=1

for _ in range((h+w-2)//2):
  dp_new=defaultdict(int)
  for i1,j1,i2,j2 in dp:
    for ni1,nj1,ni2,nj2 in [(i1-1,j1,i2+1,j2),(i1,j1-1,i2+1,j2),(i1-1,j1,i2,j2+1),(i1,j1-1,i2,j2+1)]:
      if 0<=ni1<h and 0<=nj1<w and 0<=ni2<h and 0<=nj2<w and s[ni1][nj1]==s[ni2][nj2]:
        dp_new[(ni1,nj1,ni2,nj2)]+=dp[(i1,j1,i2,j2)]
        dp_new[(ni1,nj1,ni2,nj2)]%=mod
  dp=dp_new
  
print(dp[(0,0,h-1,w-1)])