h, w = map(int, input().split())
S = [list(input()) for _ in range(h)]
mod = 10**9 + 7

m = (h + w) // 2
DP = [[[0 for _ in range(m)] for _ in range(m)] for _ in range(m)]
for k in range(m - 1, -1, -1):
    for i in range(k + 1):
        for j in range(k + 1):
            a = i
            b = k - i
            c = h - 1 - j
            d = w - 1 - (k - j)
            if 0 <= a < h and 0 <= b < w and 0 <= c < h and 0 <= d < w:
                if S[a][b] != S[c][d]:
                    continue
                if a > c or b > d:
                    continue
                if k == m - 1:
                    DP[i][j][k] = 1
                else:
                    if i < h - 1:
                        if j < h:
                            DP[i][j][k] += DP[i + 1][j + 1][k + 1]
                            DP[i][j][k] %= mod
                        DP[i][j][k] += DP[i + 1][j][k + 1]
                        DP[i][j][k] %= mod
                    if j < h:
                        DP[i][j][k] += DP[i][j + 1][k + 1]
                        DP[i][j][k] %= mod
                    DP[i][j][k] += DP[i][j][k + 1]
                    DP[i][j][k] %= mod
print(DP[0][0][0])