package main

import . "fmt"
import . "strings"

func main() {
	var n int
	Scan(&n)
	t := []byte(Repeat("a", n))
	ans := []byte(Repeat("z", n))
	Println("?", string(t))
	var x int
	Scan(&x)
	for c := byte('b'); c < 'z'; c++ {
		for i := 0; i < n; i++ {
			if ans[i] != 'z' {
				continue
			}
			t[i] = c
			Println("?", string(t))
			var y int
			Scan(&y)
			switch {
				case x < y:
					ans[i] = c
				case x > y:
					ans[i] = 'a'
			}
			x = y
		}
	}
	Println("!", string(ans))
}