H, W = map(int, input().split())
S = []
for i in range(H):
    S.append(list(input()))
    
from collections import *
Q = deque()
if S[0][0] != S[-1][-1]:
    print(0)
    exit()
    
mod = 10**9 + 7
Q.append((0, 0, H - 1, W - 1))
D = defaultdict(int)
D[(0, 0, H - 1, W - 1)] = 1
dx = [1, 0]
dy = [0, 1]
ans = 0
SS = set()
seen = set()
while Q:
    t = Q.popleft()
    sx, sy, gx, gy = t
    if gx + gy <= sx + sy + 1:
        if abs(sx - gx) + abs(sy - gy) <= 1 and t not in SS:
            SS.add(t)
            ans += D[(sx, sy, gx, gy)]
            ans %= mod
        continue
    
    for a in range(2):
        for b in range(2):
            nsx = sx + dx[a]
            nsy = sy + dy[a]
            ngx = gx - dx[b]
            ngy = gy - dy[b]
            if S[nsx][nsy] != S[ngx][ngy]:
                continue
            nt = (nsx, nsy, ngx, ngy)
            D[nt] += D[t]
            D[nt] %= mod
            if nt in seen:
                continue
            seen.add(nt)
            Q.append(nt)
            
print(ans)