#include <bits/stdc++.h>
using namespace std;
#define lli long long int
#define pb push_back
#define endl ("\n")
#define fast ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define vi vector<lli>
#define ff first
#define ss second
#define rep(i, a, b) for (lli i = a; i < b; i++)
#define repr(i, a, b) for (int i = a; i > b; i--)
#define mod 1000000007
#define all(s) s.begin(), s.end()
int main() {
    fast
    lli tt, a, b, k;
    tt = 1;
    // cin>>tt;
    while (tt--) {
        cin>>a>>b>>k;
        lli ncr[61][61], n = a + b;
        string ans = "";
        ncr[0][0] = 1;
        rep (i, 1, 61) {
            ncr[i][0] = 1;
            rep (j, 1, i + 1) {
                ncr[i][j] = ncr[i - 1][j] + ncr[i-  1][j - 1];
            }
        }
        rep (i, 0, n) {
            if (ncr[a - 1 + b][b] >= k) ans += 'a', a--;
            else ans += 'b', k -= ncr[a - 1 + b][b], b--;
        }
        cout<<ans;
    }
    return 0;
}
#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
#define DEBUG(...) debug(#__VA_ARGS__, __VA_ARGS__)
#else
#define DEBUG(...) 6
#endif

template<typename T, typename S> ostream& operator << (ostream &os, const pair<T, S> &p) {return os << "(" << p.first << ", " << p.second << ")";}
template<typename C, typename T = decay<decltype(*begin(declval<C>()))>, typename enable_if<!is_same<C, string>::value>::type* = nullptr>
ostream& operator << (ostream &os, const C &c) {bool f = true; os << "["; for (const auto &x : c) {if (!f) os << ", "; f = false; os << x;} return os << "]";}
template<typename T> void debug(string s, T x) {cerr << s << " = " << x << "\n";}
template<typename T, typename... Args> void debug(string s, T x, Args... args) {for (int i=0, b=0; i<(int)s.size(); i++) if (s[i] == '(' || s[i] == '{') b++; else
if (s[i] == ')' || s[i] == '}') b--; else if (s[i] == ',' && b == 0) {cerr << s.substr(0, i) << " = " << x << " | "; debug(s.substr(s.find_first_not_of(' ', i + 1)), args...); break;}}

const int MAX = 65;

long long choose[MAX][MAX];

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);

    for (int i=0; i<MAX; i++)
        choose[i][0] = 1;
    for (int i=1; i<MAX; i++)
        for (int j=1; j<MAX; j++)
            choose[i][j] = choose[i-1][j] + choose[i-1][j-1];

    int a, b;
    long long k;
    cin >> a >> b >> k;
    int n = a + b;

    for (int i=0; i<n; i++) {
        if (a == 0) {
            cout << 'b';
            b--;
            continue;
        }
        if (k <= choose[a+b-1][b]) {
            cout << 'a';
            a--;
        } else {
            k -= choose[a+b-1][b];
            cout << 'b';
            b--;
        }
    }
    cout << "\n";

    return 0;
}
