"""



"""

import sys
from sys import stdin

H,W,X = map(int,stdin.readline().split())
ox = X

if X % 2 == 1:
    print (-1)
    sys.exit()


S = [["."] * W for i in range(H)]
for j in range(1,W,2):
    for i in range(H):
        S[i][j] = "#"

inst = ["D"] * (H-1) + ["R"] * 2 + ["U"] * (H-1) + ["R"] * 2
x = 0
y = 0
cnt = 0
while True:

    #print (x,y)
    if x > H or y > W or x < 0 or y < 0:
        break

    if (H-1-x) + (W-1-y) == X and x%2 == 0 and y%2==0:
        while y < W-1:
            S[x][y] = "."
            y += 1
        while x < H-1:
            S[x][y] = "."
            x += 1
        for i in S:
            print ("".join(i))
        sys.exit()

    S[x][y] = "."
    if inst[cnt % len(inst)] == "D":
        x += 1
    elif inst[cnt % len(inst)] == "R":
        y += 1
    elif inst[cnt % len(inst)] == "U":
        x -= 1
    else:
        y -= 1
    X -= 1
    cnt += 1

print ("Second",file=sys.stderr)

X = ox
S = [["."] * W for i in range(H)]
inst = ["R"] * (W-1) + ["D"] * 2 + ["L"] * (W-1) + ["D"] * 2
x = 0
y = 0
cnt = 0
while True:

    if x > H or y > W or x < 0 or y < 0:
        break

    if (H-1-x) + (W-1-y) == X and x%2 == 0 and y%2==0:
        while x < H-1:
            S[x][y] = "."
            x += 1
        while y < W-1:
            S[x][y] = "."
            y += 1 
        for i in S:
            print ("".join(i))
        sys.exit()

    S[x][y] = "."
    if inst[cnt % len(inst)] == "D":
        x += 1
    elif inst[cnt % len(inst)] == "R":
        y += 1
    elif inst[cnt % len(inst)] == "U":
        x -= 1
    else:
        y -= 1
    X -= 1
    cnt += 1
        
print (-1)