#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
  #include "settings/debug.cpp"
  #define _GLIBCXX_DEBUG
#else
  #define Debug(...) void(0)
#endif
#define rep(i, n) for (int i = 0; i < (n); ++i)
using ll = long long;
using ull = unsigned long long;

inline int Query(const string& s) {
  cout << "? " << s << endl;
  int res;
  cin >> res;
  return res;
}

int main() {
  int n;
  cin >> n;
  string s(n, 'a');
  int base = Query(s);
  rep(i, n) {
    rep(j, 24) {
      s[i] = 'b' + j;
      int res = Query(s);
      if (res > base) {
        s[i] = 'b' + j;
        base = res;
        break;
      }
      else if (res < base) {
        s[i] = 'a';
        break;
      }
      if (j == 23) s[i] = 'z';
    }
  }
  cout << "! " << s << endl;
  return 0;
}