#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

void solve() {
  ll n;
  cin >> n;
  vector<ll> cnt(26, 0);
  rep(i, 26) {
    cout << "? " << string(n, 'a' + i) << endl;
    cin >> cnt[i];
  }
  string t(n, 'a');
  rep(i, n) {
    ll now = -1, resp = -1, last_j = -1;
    rep(j, 26) if (cnt[j]) {
      t[i] = 'a' + j;
      cout << "? " << t << endl;
      if (now == -1) {
        last_j = j;
        cin >> now;
        continue;
      } else {
        cin >> resp;
        if (now == resp)
          continue;
        if (now < resp) {
          last_j = j;
          now = resp;
        }
        break;
      }
    }
    cnt[last_j]--;
  }
  cout << "! " << t << endl;
}

int main() {
  std::cin.tie(nullptr);
  std::ios_base::sync_with_stdio(false);
  int T = 1;
  for (int t = 0; t < T; t++) {
    solve();
  }
  return 0;
}