h,w = map(int, input().split())

s = [input() for i in range(h)]
if s[0][0] != s[-1][-1]:
    print(0)
    exit()
n = (h+w)//2
dp = [[[0 for k in range(w)]for j in range(w)]for i in range(n)]
dp[0][0][w-1] = 1
mod = 10**9 + 7

for i in range(n-1):
    for j in range(w):
        for k in range(w):
            now = dp[i][j][k]
            if now == 0:
                continue
            #print(i,j,k)
            ni = i + 1
            nj = j
            nk = k - 1
            nx1 = ni-nj
            ny1 = nj
            nx2 = h+w-2-ni-nk
            ny2 = nk
            #print(nx1,ny1,nx2,ny2)
            if 0 <= nx1 < h and 0 <= ny1 < w and 0 <= nx2 < h and 0 <= ny2 < w and s[nx1][ny1] == s[nx2][ny2]:
                dp[ni][nj][nk] += now
                dp[ni][nj][nk] %= mod
            ni = i + 1
            nj = j
            nk = k
            nx1 = ni-nj
            ny1 = nj
            nx2 = h+w-2-ni-nk
            ny2 = nk
            if 0 <= nx1 < h and 0 <= ny1 < w and 0 <= nx2 < h and 0 <= ny2 < w and s[nx1][ny1] == s[nx2][ny2]:
                dp[ni][nj][nk] += now
                dp[ni][nj][nk] %= mod
            ni = i + 1
            nj = j + 1
            nk = k - 1
            nx1 = ni-nj
            ny1 = nj
            nx2 = h+w-2-ni-nk
            ny2 = nk
            #print(nx1,ny1,nx2,ny2)
            if 0 <= nx1 < h and 0 <= ny1 < w and 0 <= nx2 < h and 0 <= ny2 < w and s[nx1][ny1] == s[nx2][ny2]:
                dp[ni][nj][nk] += now
                dp[ni][nj][nk] %= mod
            ni = i + 1
            nj = j + 1
            nk = k
            nx1 = ni-nj
            ny1 = nj
            nx2 = h+w-2-ni-nk
            ny2 = nk
            if 0 <= nx1 < h and 0 <= ny1 < w and 0 <= nx2 < h and 0 <= ny2 < w and s[nx1][ny1] == s[nx2][ny2]:
                dp[ni][nj][nk] += now
                dp[ni][nj][nk] %= mod
if (h+w-1)%2:
    ans = 0
    for j in range(w):
        ans += dp[n-1][j][j]
        ans %= mod
    print(ans)
else:
    ans = 0
    ni = n-1
    for nj in range(w):
        for nk in range(w):
            nx1 = ni-nj
            ny1 = nj
            nx2 = h+w-2-ni-nk
            ny2 = nk
            if 0 <= nx1 < h and 0 <= ny1 < w and 0 <= nx2 < h and 0 <= ny2 < w and abs(nx1-nx2)+abs(ny1-ny2)<=1:
                ans += dp[ni][nj][nk]
                ans %= mod
    print(ans)