mod = 1000000007


def main():
    import sys
    input = sys.stdin.readline

    H, W = map(int, input().split())
    G = []
    for _ in range(H):
        G.append(input().rstrip('\n'))

    dp = [[0] * H for _ in range(H)]
    if G[0][0] != G[-1][-1]:
        print(0)
        exit()
    dp[0][H-1] = 1
    for hw in range((H + W - 2) // 2):
        dp_new = [[0] * H for _ in range(H)]
        for hl in range(H):
            wl = hw - hl
            if wl < 0 or wl >= W:
                continue
            for hr in range(H):
                wr = H + W - 2 - hw - hr
                if wr < 0 or wr >= W:
                    continue
                if hl != H - 1:
                    hl_new = hl + 1
                    sl = G[hl_new][wl]
                    if hr != 0:
                        hr_new = hr - 1
                        sr = G[hr_new][wr]
                        if sl == sr:
                            dp_new[hl_new][hr_new] = (dp_new[hl_new][hr_new] + dp[hl][hr])%mod
                    if wr != 0:
                        wr_new = wr - 1
                        sr = G[hr][wr_new]
                        if sl == sr:
                            dp_new[hl_new][hr] = (dp_new[hl_new][hr] + dp[hl][hr]) % mod
                if wl != W - 1:
                    hl_new = hl
                    sl = G[hl_new][wl+1]
                    if hr != 0:
                        hr_new = hr - 1
                        sr = G[hr_new][wr]
                        if sl == sr:
                            dp_new[hl_new][hr_new] = (dp_new[hl_new][hr_new] + dp[hl][hr]) % mod
                    if wr != 0:
                        wr_new = wr - 1
                        sr = G[hr][wr_new]
                        if sl == sr:
                            dp_new[hl_new][hr] = (dp_new[hl_new][hr] + dp[hl][hr]) % mod
        dp = dp_new

    if (H + W) & 1:
        ans = 0
        for hl in range(H):
            wl = (H + W - 2) // 2 - hl
            for hr in range(H):
                wr = (H + W - 2) // 2 + 1 - hr
                if abs(hl - hr) + abs(wl - wr) == 1:
                    if 0 <= wl < W and 0 <= wr < W:
                        ans = (ans + dp[hl][hr])%mod
        print(ans)
    else:
        ans = 0
        for hl in range(H):
            ans = (ans + dp[hl][hl])%mod
        print(ans)


if __name__ == '__main__':
    main()