#include <bits/stdc++.h>
using namespace std;

#define rep(i, n) for (int i = 0; i < (int)n; i++)

int main() {
  int N;
  cin >> N;
  string S = "";
  rep(i, N)
    S += 'z';
  cout << "? " << S << endl;
  int m;
  cin >> m;
  vector<int> a(N, 0);
  for (int i = 0; i < 25 && m < N; i++) {
    int pren = 0;
    rep(j, N) {
      if (a[j] > 0)
	continue;
      string T = S;
      T[j] = 'a' + i;
      cout << "? " << T << endl;
      int n;
      cin >> n;
      if (n < pren) {
	a[j] = 1;
      } else {
	if (n - m > 0) {
	  if (a[j] == 0) {
	    S[j] = 'a' + i;
	    a[j] = 1;
	    m++;
	  }
	}
	pren = n;
      }
      if (m == N)
	break;
    }
  }
  cout << "! " << S << endl;
  return 0;
}