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

#define all(x) begin(x), end(x)
#ifdef CKISEKI
#define safe cerr << __PRETTY_FUNCTION__ << " line " << __LINE__ << " safe\n"
#define debug(a...) debug_(#a, a)
#define orange(a...) orange_(#a, a)
void debug_(auto s, auto ...a) {
  cerr << "\e[1;32m(" << s << ") = (";
  int f = 0;
  (..., (cerr << (f++ ? ", " : "") << a));
  cerr << ")\e[0m\n";
}
#include <experimental/iterator>
void orange_(auto s, auto L, auto R) {
  cerr << "\e[1;33m[ " << s << " ] = [ ";
  using namespace experimental;
  copy(L, R, make_ostream_joiner(cerr, ", "));
  cerr << " ]\e[0m\n";
}
#else
#define safe ((void)0)
#define debug(...) safe
#define orange(...) safe
#endif

char BASE[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";

int ask(string s) {
  puts(s.c_str());
  fflush(stdout);
  string access, status;
  cin >> access >> status;
  if (status == "GRANTED") {
    exit(0);
  }
  string t, ms;
  cin >> t >> ms;
  t.erase(t.begin());
  return stoi(t);
}

int main() {
  int len = -1;
  for (int i = 1; i <= 20; ++i) {
    int t = ask(string(i, 'a'));
    if (t != 5) {
      len = i;
      break;
    }
  }
  int base = 14, dlt = 9;
  string ans(len, 'a');
  for (int i = 0; i < len; ++i) {
    for (int j = 0; j < 62; ++j) {
      ans[i] = BASE[j];
      if (ask(ans) != base + dlt * i)
        break;
    }
  }
  return 0;
}