# 

TAR = 'helloworld'
TLEN = len(TAR)

t0 = int(input())
for i0 in range(t0):
    n = int(input())
    s = input()
    res = ''
    for i in range(n-TLEN+1):
        ok = True
        for j in range(TLEN):
            if s[i+j]!='?' and s[i+j]!=TAR[j]:
                ok = False
                break
        if not ok:
            continue
        ts = (s[:i] + TAR + s[i+TLEN:]).replace('?', 'a')
        if not res or ts < res:
            res = ts
    if not res:
        print(-1)
    else:
        print(res)