import sys
def input():return sys.stdin.readline().strip()
mem={}
def calc(a,b,c,d,S,H,W):
    if S[a][b]!=S[c][d] or a>c or b>d:
        return 0
    if a+b==c+d:
        return (a==c) and (b==d)
    if a+b+1==c+d:
        return (a==c) or (b==d)
    if not (a*W+b)*H*W+(c*W+d) in mem:
        mem[(a*W+b)*H*W+(c*W+d)]=calc(a+1,b,c-1,d,S,H,W)+calc(a+1,b,c,d-1,S,H,W)+calc(a,b+1,c-1,d,S,H,W)+calc(a,b+1,c,d-1,S,H,W)
        mem[(a*W+b)*H*W+(c*W+d)]%=(10**9+7)
    return mem[(a*W+b)*H*W+(c*W+d)]

H,W=map(int,input().split())
S=[input() for i in range(H)]
print(calc(0,0,H-1,W-1,S,H,W))