# Read the input lines until 0 is encountered
import sys

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

for line in sys.stdin:
    num = int(line.strip())
    if num == 0:
        break
    if num in mapping:
        print(mapping[num])
    else:
        # Handle numbers not in the mapping (though problem constraints may imply they are covered)
        print('?')