MOD = 998244353


def main():
    H, W, K, C = open(0).read().split(maxsplit=3)
    H, W, K = int(H), int(W), int(K)
    dp = [0] * (H * W)
    stair = [0] * (H * W)
    dacc = [0] * (H * W)
    for i in range(H):
        hacc = [0] * W
        for j in range(W):
            x = 0
            if i == 0 and j == 0:
                dp[0] += 1
            else:
                if i > 0:
                    x += stair[(i - 1) * W + j]
                if j > 0:
                    x += hacc[j - 1]
                if j >= K + 1:
                    x -= hacc[j - K - 1]
                p = max(0, K - j)
                if i >= p + 1:
                    x -= dacc[(i - p - 1) * W + j + p - K]
                if i >= K + 2 and j + 1 < W:
                    x += dacc[(i - K - 2) * W + j + 1]
                x %= MOD
                if C[i * (W + 1) + j] == ".":
                    dp[i * W + j] = x

            stair[i * W + j] = (x + dp[i * W + j]) % MOD
            dacc[i * W + j] = dp[i * W + j]
            if i > 0 and j + 1 < W:
                dacc[i * W + j] = (dacc[i * W + j] + dacc[(i - 1) * W + j + 1]) % MOD
            hacc[j] = dp[i * W + j]
            if j > 0:
                hacc[j] = (hacc[j] + hacc[j - 1]) % MOD

    print(dp[-1])


if __name__ == "__main__":
    main()