for i in range(int(input())):
	n = int(input())
	s = input()
	c = 0
	for i in range(s):
		if s[i] == "helloworld"[c] or s[i] == "?":
			c += 1
			if c == 10:
				print(c[:i-9] + "helloworld" + c[i+1:])
				break
		else:
			c = 0
	print(-1)