/*
 * author:  ADMathNoob
 * created: 05/09/24 14:52:55
 * problem: https://qoj.ac/problem/2292
 */

/*
Comments about problem:


*/

#include <bits/stdc++.h>

using namespace std;

#ifdef _DEBUG
#include "debug.h"
#else
#define debug(...) 42
#endif

int Ask(string s) {
  cout << s << endl;
  string r;
  cin >> r;
  cin >> r;
  if (r == "GRANTED") {
    exit(0);
  }
  cin >> r;
  string tmp;
  cin >> tmp;
  return stoi(r.substr(1));
}

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  string all = "";
  for (int i = 0; i < 26; i++) {
    all += (char) ('A' + i);
    all += (char) ('a' + i);
  }
  for (int i = 0; i < 10; i++) {
    all += (char) ('0' + i);
  }

  int len = 1;
  while (true) {
    if (Ask(string(len, 'a')) == 5) {
      len += 1;
    } else {
      break;
    }
  }
  string ret = "";
  for (int i = 0; i < len; i++) {
    for (char c : all) {
      string s = ret + c + string(len - 1 - i, 'a');
      int r = Ask(s);
      int pref = (r - 14) / 9;
      if (pref >= i + 1) {
        ret += c;
        break;
      }
    }
  }
  return 0;
}