#include<bits/stdc++.h>
using namespace std;
int main() {
  int N;
  cin >> N;
  string ans = string(N, '0');
  for (int i = 0; i < N; i++) {
    string T = string(N, 'a');
    int pre = -10;
    for (int j = 0; j < 25; j++) {
      T[i] = char('a' + j);
      cout << "? " << T << endl;
      int n;
      cin >> n;
      if (n < pre) {
        ans[i] = char(T[i] - 1);
        break;
      }
      pre = n;
    }    
    if (ans[i] == '0') {
      ans[i] = 'z';
    }
  }
  cout << "! " << ans << endl;
}