t = int(input())

for i in range(1, t+1):
    n = int(input())
    arr = list(map(int, input().split()))

    color_freq = {}
    for c in arr:
        if c not in color_freq:
            color_freq[c] = 1

    colors = sorted(color_freq.keys())

    impossible = False
    result = [-1] * n

    for idx, color in enumerate(colors):
        color_idx = [i for i in range(n) if arr[i] == color]
        num_cards = len(color_idx)

        if idx == 0:
            if num_cards > 1:
                impossible = True
                break

            result[color_idx[0]] = 1
            continue

        if num_cards == 1:
            result[color_idx[0]] = max(result[color_idx[0]-1] + 1, 1)
        else:
            diff = result[color_idx[0]] - result[color_idx[1]]
            if diff < 0:
                impossible = True
                break

            for i in range(1, num_cards):
                if result[color_idx[i-1]] - result[color_idx[i]] != diff:
                    impossible = True
                    break

                result[color_idx[i]] = result[color_idx[i-1]]

            if impossible:
                break

    if impossible:
        print("Case #{}: IMPOSSIBLE".format(i))
    else:
        print("Case #{}: {}".format(i, " ".join(str(result[i]) for i in range(n)))))