t = int(input())
h='helloworld'

for _ in range(t):

    n=int(input())
    s=input()
    F = 0
    if n < 10:
        print(-1)
        continue

    ans=[]
    for i in range(n-len(h),-1,-1):
        f = 0
        an = []
        for j in range(len(h)):
            if s[i+j] == h[j] or s[i+j] == '?':
                continue
            else:
                f = 1
                break
        if f == 0:
            F=1
            for k in range(n):
                if i<= k  <= i + len(h) - 1:
                    an.append(h[k-i])
                else:
                    if s[k] =='?':
                        an.append('a')
                    else:
                        an.append(s[k])
            ans.append(an)
            
    if F == 0:
        print(-1)
    else:
        ans.sort()
        print(''.join(ans[0]))