#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 right = -1;
    for (int i = n - 1; i >= m; i--) {
      if (Z[i] >= 10) {
        right = i;
        break;
      }
    }
    if (right == -1) {
      cout << -1 << '\n';
      continue;
    }

    for (int j = 0; j < n; j++) {
      if (t[j] == '?') {
        if (j >= right) {
          t[j] = S[j - right];
        } else {
          t[j] = 'a';
        }
      }
    }

    for (int i = right - 1; i >= m; i--) {
      if (Z[i] >= m) {
        bool ok = false;
        for (int j = 0; j < m; j++) {
          if (t[i + j] > S[j]) {
            ok = true;
            break;
          }
          if (t[i + j] < S[j]) {
            ok = false;
            break;
          }
        }
        if (ok) {
          for (int j = 0; j < m; j++) {
            t[i + j] = S[j];
          }
          for (int j = i + m; j < n; j++) {
            t[j] = 'a';
          }
        }
      }
    }

    cout << t.substr(m) << '\n';
  }

  return 0;
}