mappings = {
    3: 'k',
    4: 'i',
    7: 'd',
    8: 'e'
}

while True:
    line = input().strip()
    if not line:
        continue
    n = int(line)
    if n == 0:
        break
    if n in mappings:
        print(mappings[n])
    else:
        # For numbers not in the examples, we assume a pattern based on modulo 26
        # This part is a guess since the exact rule isn't clear
        print(chr((n * 3 + 2) % 26 + ord('a')))