mod=10**9+7

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

def check(x,y):
  return 0<=x<h and 0<=y<w

dp=[[[0]*h for i in range(w)] for j in range(h)]
if (h+w)%2==0:
  for i1 in range(h):
    j1=(h+w-2)//2-i1
    if 0<=j1<w:
      dp[i1][j1][i1]=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 check(i2,j2) and s[i1][j1]==s[i2][j2]:
          dp[i1][j1][i2]=1

dx1=[-1,0]
dy1=[0,-1]
dx2=[1,0]
dy2=[0,1]

for m in range((h+w-2)//2,0,-1):
  for i1 in range(h):
    j1=m-i1
    if not 0<=j1<w:
      continue
    for i2 in range(h):
      j2=h+w-2-m-i2
      if not 0<=j2<w:
        continue
      for di1,dj1 in zip(dx1,dy1):
        for di2,dj2 in zip(dx2,dy2):
          ni1,nj1,ni2,nj2=i1+di1,j1+dj1,i2+di2,j2+dj2
          if check(ni1,nj1) and check(ni2,nj2) and s[ni1][nj1]==s[ni2][nj2]:
            dp[ni1][nj1][ni2]+=dp[i1][j1][i2]
            dp[ni1][nj1][ni2]%=mod
  
print(dp[0][0][h-1])