#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using ll = long long;
using ull = unsigned long long;
using mint = atcoder::modint998244353;
using maxt = atcoder::modint1000000007;
vector<ll> Era(int N) {
  vector<ll> ans(0, 0);
  vector<bool> isprime(N + 1, true);
  isprime.at(1) = false;
  for(int i = 1; i <= N; i++) {
    if(isprime.at(i)) {
      ans.push_back(i);
      for(int j = 2 * i; j <= N; j += i) {
        isprime.at(j) = false;
      }
    }
  }
  return ans;
}
ll POW(ll a, int N) {
  if(N == 1) {
    return a;
  }
  ll ans = POW(a, N / 2) * POW(a, N / 2);
  if(N % 2 == 1) {
    ans *= a;
  }
  return ans;
}

//ライブラリここまで

int main() {
  int alpha;
  cin >> alpha;
  set<string> str;
  for(int i = 0; i < 26; i++) {
    for(int j = 0; j < 26; j++) {
      string tmp = "";
      tmp += (char)(i + 65);
      tmp += (char)(j + 65);
      str.insert(tmp);
    }
  }
  char ans = '?';
  while(ans != '!') {
    string tmp = "";
    for(string o : str) {
      if(o.at(0) == alpha) {
        cout << o << endl;
        tmp = o;
        break;
      }
    }
    str.erase(tmp);
    cin >> ans >> tmp;
    str.erase(tmp);
  }
}