import random


def main():
    alphas = [chr(ord('a') + i) for i in range(26)]
    ans = []

    N = int(input())

    for i in range(N):
        random.shuffle(alphas)

        T = ['a' for _ in range(N)]
        counts_max = None

        for x in alphas:
            T[i] = x

            print(*T, sep="", flush=True)
            c = int(input())

            if counts_max is None:
                counts_max = c
            else:
                if counts_max < c:
                    ans.append(x)
                    break

    print(*ans, sep='')


main()