import sys
input = sys.stdin.readline

X="helloworld"

T=int(input())
for tests in range(T):
    N=int(input())
    S=list(input().strip())

    flag=0

    for i in range(N):
        if S[i:i+10]=="helloworld":
            flag=1

    if flag==1:
        for i in range(N):
            if S[i]=="?":
                S[i]="a"

            print("".join(S))
            continue

    for i in range(N-10,-1,-1):
        flag=1
        for j in range(10):
            if S[i+j]=="?" or S[i+j]==X[j]:
                True
            else:
                flag=0

        if flag==1:
            for j in range(10):
                if S[i+j]=="?":
                    S[i+j]=X[j]

            for i in range(N):
                if S[i]=="?":
                    S[i]="a"

            print("".join(S))
            break

    else:
        print(-1)