#include<bits/stdc++.h>

using namespace std;

int main()
{
//  ios::sync_with_stdio(0);
//  cin.tie(0);
    map<int, char> mp;
    int ch = -25;
    for(int i = 0; i < 26; i++)
        mp[ch] = char(i + 'a'), ch += 2;
    int n;
    cin >> n;
    string s;
    for(int i = 0; i < n; i++)
        s.push_back('a');
    for(int i = 0; i < n; i++)
    {
        cout << s << endl;
        int before = -1;
        cin >> before;
        if(before == 0)
            return 0;
        s[i] = 'z';
        cout << s << endl;
        int after = -1;
        cin >> after;
        if(after == 0)
            return 0;
        s[i] = mp[before - after];
    }
    cout << s << endl;
}