int input def gcd while and if else return letters sorted list QWERTYU

t = int(input())


def gcd(u, v):
    while u > 0 and v > 0:
        if u > v:
            u %= v
        else:
            v %= u
    return u + v


letters = sorted(list('QWERTYUIOPASDFGHJKLZXCVBNM'))

for test_num in range(1, t + 1):
    line1 = input()
    d = list(map(int, input().split(' ')))
    n = len(d)
    r = [None] * (n + 1)
    for i in range(n):
        if d[i] != d[i + 1]:
            c = gcd(d[i], d[i + 1])
            r[i+1] = c
            for j in range(i, -1, -1):
                r[j] = d[j] // r[j+1]
            for j in range(i+1, n+1):
                r[j] = d[j-1] // r[j-1]
            break

    nums = sorted(list(set(r)))
    code = {k: v for k, v in zip(nums, letters)}
    out = [code[v] for v in r]
    result = ''.join(out)
    print("Case #{}: {}".format(test_num, result))