import sys

def printfl(*args, **kwargs):
	print(*args, **kwargs)
	sys.stdout.flush()

T = int(input())

for t in range(1, T+1):
	N = int(input())
	
	n_min = 0 # allowed
	n_max = N # not allowed
	
	while n_max - n_min > 1:
		n_mid = (n_min+n_max)//2
		if 26*n_mid*(n_mid+1)//2 < N:
			n_min = n_mid
		else:
			n_max = n_mid
	
	N -= 26*n_min*(n_min+1)//2
	ans = chr(ord('A') + (N-1)//n_max)
	
	print(f"Case #{t}: {ans}")