mapping = {
    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 mapping:
        print(mapping[n])
    else:
        # Fallback to alphabet if not in special cases
        print(chr(n % 26 + ord('a')))