import sys
import math
import collections
import bisect
import itertools
import decimal
import copy

# import numpy as np

# sys.setrecursionlimit(10 ** 6)
INF = 10 ** 20
MOD = 10 ** 9 + 7
# MOD = 998244353

ni = lambda: int(sys.stdin.readline().rstrip())
ns = lambda: map(int, sys.stdin.readline().rstrip().split())
na = lambda: list(map(int, sys.stdin.readline().rstrip().split()))
na1 = lambda: list(map(lambda x: int(x) - 1, sys.stdin.readline().rstrip().split()))


# ===CODE===


def main():
    s = input()
    c = ord("a")

    for i, si in enumerate(s):
        if si != chr(c + i):
            before = chr(c + i)
            after = si
            print(before + "to" + after)
            break


if __name__ == '__main__':
    main()