#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_algo1(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]) {
      a++;
    }
    if (until < i + a) {
      until = i + a;
      from = i;
    }
  }
  Z[0] = n;
  return Z;
}

static inline vector<int> z_algo2(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$";
  while (T--) {
    cin >> n >> s;
    string t = S + s;
    auto Z1 = z_algo1(t);
    auto Z2 = z_algo2(t);
    bool ok = false;
    int l = Z1.size(), r = l;
    for (int i = Z1.size() - 1; i >= S.size(); i--) {
      if (Z1[i] >= 10) {
        ok = true;
        break;
      }
    }
    if (ok) {
      for (int i = 0; i < Z1.size(); i++) {
        if (t[i] == '?')
          t[i] = 'a';
      }
    } else {
      for (int i = Z2.size() - 1; i >= (int)S.size(); i--) {
        if (Z2[i] >= 10) {
          ok = true;
          for (int j = 0; j < i; j++) {
            if (t[j] == '?')
              t[j] = 'a';
          }
          for (int j = 0; j < 10; j++) {
            if (t[i + j] == '?') {
              t[i + j] = S[j];
            }
          }
          for (int j = i + 10; j < (int)Z2.size(); j++) {
            if (t[j] == '?')
              t[j] = 'a';
          }
        }
      }
    }

    if (!ok)
      cout << -1 << '\n';
    else
      cout << t.substr(S.size()) << '\n';
  }

  return 0;
}