#include <algorithm>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <vector>
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define replr(i, l, r) for (int i = (l); i < (r); ++i)
const int mod = 1e9 + 7;
ll a, b, k;
ll ncr(ll n, ll r) {
    ll res = 1;
    rep(i, r) {
        res *= n - i;
        res /= (i + 1);
    }
    return res;
}

int main() {

    cin >> a >> b >> k;

    string ans = "";
    k--;
    while (a > 0 && b > 0) {
        ll x = ncr(a + b - 1, b);
        if (k < x) {
            ans += "a";
            a--;
        } else {
            ans += "b";
            b--;
            k -= x;
        }
    }
    rep(i, a) ans += "a";
    rep(i, b) ans += "b";
    cout << ans << endl;

    return 0;
}
/**
 *  author: souravrax
 *  created: 22.05.2021 17:50:47
**/
#include <bits/stdc++.h>
using namespace std;

#define all(x) begin(x), end(x)
#define len(x) int((x).size())
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> 
ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#ifdef LOCAL
#define dbg(...) cerr << "[ " << #__VA_ARGS__ << " ]:", dbg_out(__VA_ARGS__)
#else
#define dbg(...) (void)0x30
#endif
using ll = long long;

ll memo[35][35];

ll dp(ll a, ll b) {
    if (a == 0 || b == 0) return memo[a][b] = 1;
    ll ans = memo[a][b];
    if (~ans) return ans;
    return memo[a][b] = dp(a - 1, b) + dp(a, b - 1);
}

int32_t main() {
    ios::sync_with_stdio(false), cin.tie(nullptr);
    ll a, b, k;
    cin >> a >> b >> k, k--;

    ll now = k;
    memset(memo, -1, sizeof memo);

    ll _a = a, _b = b;
    string ans;

    for (int i = 0; i < a + b; i++) {
        if (_a == 0) {
            ans.push_back('b');
            _b--;
            continue;
        }
        if (_b == 0) {
            ans.push_back('a');
            _a--;
            continue;
        }

        if (dp(_a - 1, _b) > now) {
            _a--;
            ans.push_back('a');
        } else {
            now -= dp(_a - 1, _b);
            _b--;
            ans.push_back('b');
        }
    }
    cout << ans << '\n';
}

