MOD = 10**9 + 7

H, W = map(int, input().split())
grid = [input().strip() for _ in range(H)]

total_steps = H + W - 2
if total_steps % 2 != 0:
    print(0)
    exit()

m = total_steps // 2

from collections import defaultdict

def generate_a(k):
    a_list = []
    for x in range(1, H + 1):
        y = k + 2 - x
        if 1 <= y <= W:
            a_list.append((x, y))
    return a_list

def generate_b(k):
    b_list = []
    target_sum = H + W - k
    for x in range(1, H + 1):
        y = target_sum - x
        if 1 <= y <= W:
            b_list.append((x, y))
    return b_list

current_dp = defaultdict(int)

# Initialize for k=0
a0 = (1, 1)
b0 = (H, W)
if grid[a0[0]-1][a0[1]-1] == grid[b0[0]-1][b0[1]-1]:
    current_dp[(a0, b0)] = 1

for k in range(m):
    next_dp = defaultdict(int)
    for (a, b), cnt in current_dp.items():
        # Generate possible moves from a (right or down)
        a_moves = []
        x, y = a
        if y + 1 <= W:
            a_moves.append((x, y + 1))
        if x + 1 <= H:
            a_moves.append((x + 1, y))
        # Generate possible moves from b (left or up)
        bx, by = b
        b_moves = []
        if by - 1 >= 1:
            b_moves.append((bx, by - 1))
        if bx - 1 >= 1:
            b_moves.append((bx - 1, by))
        # Check all combinations
        for a_new in a_moves:
            for b_new in b_moves:
                if grid[a_new[0]-1][a_new[1]-1] == grid[b_new[0]-1][b_new[1]-1]:
                    next_dp[(a_new, b_new)] = (next_dp[(a_new, b_new)] + cnt) % MOD
    current_dp = next_dp

# Sum all pairs where a == b
answer = 0
for (a, b), cnt in current_dp.items():
    if a == b:
        answer = (answer + cnt) % MOD

print(answer)