Buggy python submission (verdict: Runtime Error):
attern = {
        0:["#", "."],
        1:[".", "#"],
    }

    while True:
        (H, W) = [int(i) for i in input().split())]
        if H == W == 0:
            break
        for j in range(H):
            p = pattern[j % 2]
            print (.join([p[i % 2] for i in range(W)]))
            print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
        0:["#", "."],
        1:[".", "#"],
    }

    while True:
        (H, W) = [int(i) for i in input().split())]
        if H == W == 0:
            break
        for j in range(H):
            p = pattern[j % 2]
            print (.join([p[i % 2] for i in range(W)]))
            print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
        0:["#", "."],
        1:[".", "#"],
}

while True:
    (H, W) = [int(i) for i in input().split())]
    if H == W == 0:
        break
    for j in range(H):
        p = pattern[j % 2]
        print (.join([p[i % 2] for i in range(W)]))
        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
    0:["#", "."],
    1:[".", "#"],
}

while True:
    (H, W) = [int(i) for i in input().split())]
    if H == W == 0:
        break
    for j in range(H):
        p = pattern[j % 2]
        print (.join([p[i % 2] for i in range(W)]))
        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
    0:["#", "."],
    1:[".", "#"],
}

while True:
    (H, W) = [int(i) for i in input().split())]
    if H == W == 0:
        break
    for j in range(H):
        p = pattern[j % 2]
        print (.join([p[i % 2] for i in range(W)]))
        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
    0: ["#", "."],
    1: [".", "#"],
}

while True:
    (H, W) = [int(i) for i in input().split())]
    if H == W == 0:
        break
for j in range(H):
        p = pattern[j % 2]
        print(.join([p[i % 2] for i in range(W)]))
        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
        0:["#", "."],
        1:[".", "#"],
    }

while True:
    (H, W) = map(int, raw_input().split())
    if H == W == 0:
        break
    for j in range(H):
        p = pattern[j % 2]
        print ("join([p[i % 2] for i in range(W)]))
    print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
        0:["#", "."],
        1:[".", "#"],
    }

while True:
    (H, W) = [int(i) for i in input().split()]
    if H == W == 0:
        break
    for j in range(H):
        p = pattern[j % 2]
        print ("join([p[i % 2] for i in range(W)]))
    print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
pattern = {
        0:["#", "."],
        1:[".", "#"],
    }

while True:
    (H, W) = [int(i) for i in input().split()]
    if H == W == 0:
        break
    for i in range(H):
        p = pattern[i % 2]
        print ("join([p[i % 2] for i in range(W)]))
    print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(w):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(w):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
    for w in range(W):
        if (h + w) % 2 == 0:
            print('#', end='')
        else:
            print('.', end='')

    print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()

Buggy python submission (verdict: Runtime Error):
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(h):
        for w in range(w):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()

Fixed submission:
while True:
    H, W = [int(i) for i in input().split()]
    if H == W == 0:
        break

    for h in range(H):
        for w in range(W):
            if (h + w) % 2 == 0:
                print('#', end='')
            else:
                print('.', end='')

        print()
    print()