import sys

inputs = sys.stdin.readline

"""再帰関数のときセット
sys.setrecursionlimit(10**7)
import pypyjit
pypyjit.set_param('max_unroll_recursion=-1')
"""


def main():
    CONST = "helloworld"

    def solve():
        N = int(inputs())
        S = input()
        left, right = N - 10, N
        while left >= 0:
            is_ok = True
            for i in range(10):
                if S[left + i] == '?':
                    continue
                if S[left + i] != CONST[i]:
                    is_ok = False
                    break
            if not is_ok:
                left -= 1
                right -= 1
                continue
            print(S[:left].replace('?', 'a') + CONST + S[right:].replace('?',
                                                                         'a'))
            return
        print(-1)

    T = int(inputs())
    for _ in range(T):
        solve()


if __name__ == '__main__':
    main()