const int mod = 1e9 + 7;
int p[100100];

string gen_str() {
    string s;
    forn(i, 0, 20) {
        s += 'a' + rnd() % 26;
    }
    return s;
}

int get_hash(string s, int start) {
    int h = 0;
    forn(i, 0, sz(s)) {
        h = (h * 1ll * p[1] + s[i] - 'a' + 1) % mod;
    }
    h = h * 1ll * p[start] % mod;
    return h;
}

void solve(){
    int P, h;
    cin >> P >> h;
    forn1(i, 0, 100000) {
        p[i] = (i == 0 ? 1 : p[i - 1] * 1ll * P % mod);
    }
    unordered_map<int, string> st;
    forn(i, 0, 1e5) {
        string a = gen_str();
        st[get_hash(a, 20)] = a;
    }
    forn(i, 0, 1e5) {
        string a = gen_str();
        int hash = get_hash(a, 0);
        if (st.contains((h - hash + mod) % mod)) {
            cout << st[(h - hash + mod) % mod] << a << endl;
            return;
        }
    }
}