#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define ov4(a, b, c, d, name, ...) name
#define rep3(i, a, b, c) for(ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for(ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for(auto &&e : v)
#define all(a) begin(a), end(a)
#define si(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S> bool chmin(T &a, const S &b) { return a > b ? a = b, 1 : 0; }
template <typename T, typename S> bool chmax(T &a, const S &b) { return a < b ? a = b, 1 : 0; }

const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;

#define i128 __int128_t

struct _ {
    _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

vi lcp(string s) {
    vector<string> res;
    rep(i, si(s)) res.eb(s.substr(i));
    sort(all(res));
    vi ans;
    rep(i, si(res) - 1) {
        bool found = false;
        rep(j, 1, min(si(res[i]), si(res[i + 1])) + 1) {
            if(res[i].substr(0, j) != res[i + 1].substr(0, j)) {
                ans.eb(j - 1);
                found = true;
                break;
            }
        }
        if(!found) ans.eb(min(si(res[i]), si(res[i + 1])));
    }
    return ans;
}

template <typename T> ostream &operator<<(ostream &os, vector<T> v) {
    os << "[";
    fore(e, v) os << e << ", ";
    return os << "]";
}
template <typename T, typename S> ostream &operator<<(ostream &os, pair<T, S> p) { return os << "(" << p.first << ", " << p.second << ")"; }

struct edge {
    int x, y, idx;
};
vector<edge> eulerian_path(vector<edge> es, int s, bool directed = false) {
    if(es.empty()) return {};
    int n = 0;
    fore(e, es) chmax(n, max(e.x, e.y) + 1);
    vector<vector<pair<edge, int>>> g(n);
    for(auto &e : es) {
        int p = si(g[e.y]);
        g[e.x].emplace_back(e, p);
        if(!directed) {
            int q = si(g[e.x]) - 1;
            swap(e.x, e.y);
            g[e.x].emplace_back(e, q);
        }
    }
    vector<edge> ord;
    stack<pair<int, edge>> st;
    st.emplace(s, edge{-1, -1, -1});
    while(st.size()) {
        int x = st.top().first;
        if(empty(g[x])) {
            ord.eb(st.top().second);
            st.pop();
        } else {
            auto e = g[x].back();
            g[x].pop_back();
            if(e.second == -1) continue;
            if(!directed) g[e.first.y][e.second].second = -1;
            st.emplace(e.first.y, e.first);
        }
    }
    ord.pop_back();
    reverse(begin(ord), end(ord));
    if(si(ord) != si(es)) return {};
    return ord;
}

int main() {
    int t;
    cin >> t;
    rep(t) {
        int n;
        cin >> n;
        if(n == 2) {
            cout << "ab" << endl;
            continue;
        }
        int m = 1;
        while((1 << m) + (m - 1) < n) m++;

        vector<edge> E;
        rep(b, 1 << (m - 1)) {
            rep(j, 2) {
                int nb = ((b << 1) | j) & ~(1 << m - 1);
                E.push_back(edge{(int)b, nb, (int)j});
            }
        }
        assert(si(E) == (1 << m));
        auto res = eulerian_path(E, 0, true);
        string s(m, 'a');
        int i = 0;
        while(si(s) < n) {
            s += 'a' + (res[i].idx);
            i++;
        }
        reverse(all(s));
        cout << s << endl;
        // cout << lcp(s) << endl;
    }
}