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

for _ in range(t):

    n=int(input())
    s=input()
    F = 0
    for i in range(n-len(h),-1,-1):
        f = 0
        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:
                    print(h[k-i],end='')
                else:
                    if s[k] =='?':
                        print('a',end='')
                    else:
                        print(s[k],end='')
            print()
            break
    if F == 0:
        print(-1)