#include<bits/stdc++.h>
using namespace std;
const int INF = 1e9;
int main() {
  int N;
  cin >> N;
  string ans = string(N, 'a');
  for (int i = 0; i < N; i++) {
    int MAX = 0, MIN = INF;
    char c = 'a';
    for (int j = 0; j < 25; j++) {
      ans[i] = 'a' + j;
      cout << "? " << ans << endl;
      int n;
      cin >> n;
      if (n > MAX) {
        MAX = n;
        c = ans[i];
      }
      MIN = min(MIN, n);
    }    
    if (MIN == MAX) {
      c = 'z';
    }
    ans[i] = c;
  }
  cout << "! " << ans << endl;
}