import sys
input = sys.stdin.readline


def enc(i, j, S):
    return 4*(W*i+j)+S


def move(i, j, S):
    di = -1 if S & 1 else 1
    if 0 <= i + di < H:
        i += di
    else:
        S ^= 1
    dj = -1 if S & 2 else 1
    if 0 <= j + dj < W:
        j += dj
    else:
        S ^= 2
    return i, j, S


H, W = map(int, input().split())
K = int(input())
ans = [[0] * W for _ in range(H)]
time = [-1] * (4*H*W)
t = i = j = S = 0
while time[enc(i, j, S)] == -1:
    time[enc(i, j, S)] = t
    t += 1
    ans[i][j] ^= 1
    i, j, S = move(i, j, S)


t1 = time[enc(i, j, S)]
dt = t - t1
n, t2 = divmod(K - t1, dt)

for _ in range(dt):
    ans[i][j] ^= n % 2
    i, j, S = move(i, j, S)
for _ in range(t2):
    ans[i][j] ^= 1
    i, j, S = move(i, j, S)

for row in ans:
    print(''.join(map(lambda x: ".#"[x], row)))