#include <cctype>
#ifndef SHO_LOCAL
#include <bits/stdc++.h>
#define debug(...) ;
#else
#include "debug.h"
#endif
#define all(x) (x).begin(), (x).end()
#define lb(x, a) lower_bound(all(x), (a)) - (x).begin()
typedef long long ll;
using namespace std;

static inline vector<int> z_algo(const string &s) {
  int n = (int)s.size();
  vector<int> Z(n);
  int from = -1, until = -1;
  for (int i = 1; i < n; i++) {
    int &a = Z[i];
    if (from != -1) {
      a = max(0, min(Z[i - from], until - i));
    }
    while (i + a < n && (s[i + a] == s[a] || s[i + a] == '?' || s[a] == '?')) {
      a++;
    }
    if (until < i + a) {
      until = i + a;
      from = i;
    }
  }
  Z[0] = n;
  return Z;
}

int main() {
  iostream::sync_with_stdio(0), cin.tie(0);

  int T;
  cin >> T;
  int n;
  string s;
  const string S = "helloworld";
  int m = (int)S.size();
  while (T--) {
    cin >> n >> s;
    string t = S + s;
    auto Z = z_algo(t);
    n = (int)t.size();

    int left = -1;
    for (int i = m; i < n; i++) {
      if (Z[i] >= 10) {
        left = i;
        break;
      }
    }
    if (left == -1) {
      cout << -1 << '\n';
      continue;
    }
    int right = left;
    for (int i = m - 1; i > left; i--) {
      if (Z[i] >= 10) {
        right = i;
        break;
      }
    }
    int ans = right;
    if (left != right && left + 9 >= right) {
      int len = right + 10 - left;
      string temp = t.substr(left, len);
      int diff = right - left;
      for (int j = 0; j < m; j++) {
        temp[j + diff] = S[j];
      }
      for (int j = 0; j < diff; j++) {
        if (temp[j] == '?')
          temp[j] = 'a';
      }

      bool f = false;
      for (int j = 0; j < m; j++) {
        if (!f && temp[j] < S[j])
          break;
        if (S[j] < temp[j]) {
          f = true;
        }
        temp[j] = S[j];
      }
      for (int j = 0; j < len; j++) {
        t[left + j] = temp[j];
      }
    } else {
      for (int j = 0; j < m; j++) {
        t[left + j] = S[j];
      }
    }
    for (int j = 0; j < n; j++) {
      if (t[j] == '?')
        t[j] = 'a';
    }
    cout << t.substr(m) << '\n';
  }

  return 0;
}