#include <bits/stdc++.h>
long long c[61][61];
using namespace std;
int main(){
	c[0][0]=1;
	for(int i=1;i<=60;i++){
		c[i][0]=1;
		for(int j=1;j<=i;j++){
			c[i][j]=c[i-1][j-1]+c[i-1][j];
		}
	}
	int a,b;
	long long k;
	cin>>a>>b>>k;
	int n=a+b;
	for(int i=1;i<=n;i++){
		if(c[n-i][b]>=k){
			cout<<'a';
			a--;
		}
		else{
			cout<<'b';
			k-=c[n-i][b];
			b--;
		}
	}
	return 0;
}
#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <tuple>
#include <utility>
#include <vector>

#define rep(i, a, b) for (int i = int(a); i < int(b); i++)
using namespace std;
using ll = long long int;
using P = pair<ll, ll>;

// clang-format off
#ifdef _DEBUG_
#define dump(...) do{ cerr << __LINE__ << ":\t" << #__VA_ARGS__ << " = "; debug_print(__VA_ARGS__); } while(false)
template<typename T, typename... Ts> void debug_print(const T &t, const Ts &...ts) { cerr << t; ((cerr << ", " << ts), ...); cerr << endl; }
#else
#define dump(...) do{ } while(false)
#endif
template<typename T> vector<T> make_v(size_t a, T b) { return vector<T>(a, b); }
template<typename... Ts> auto make_v(size_t a, Ts... ts) { return vector<decltype(make_v(ts...))>(a, make_v(ts...)); }
template<typename T> bool chmin(T &a, const T& b) { if (a > b) {a = b; return true; } return false; }
template<typename T> bool chmax(T &a, const T& b) { if (a < b) {a = b; return true; } return false; }
template<typename T, typename... Ts> void print(const T& t, const Ts&... ts) { cout << t; ((cout << ' ' << ts), ...); cout << '\n'; }
template<typename... Ts> void input(Ts&... ts) { (cin >> ... >> ts); }
template<typename T> istream &operator,(istream &in, T &t) { return in >> t; }
// clang-format on

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int a, b;
    ll k;
    input(a, b, k);
    auto comb = make_v(100, 100, 0LL);
    auto nCr = [&](auto &f, int n, int r) -> ll {
        if (r == 0 || n == r) {
            return 1;
        }
        if (comb[n][r] > 0) return comb[n][r];
        return comb[n][r] = f(f, n - 1, r) + f(f, n - 1, r - 1);
    };
    string ans = "";
    int n = a + b;
    rep(i, 0, n) {
        if (a > 0) {
            ll cnt = nCr(nCr, a + b - 1, b);
            dump(k, cnt, a, b);
            if (k > cnt) {
                k -= cnt;
                ans += 'b';
                b--;
            } else {
                ans += 'a';
                a--;
            }
        } else {
            ans += 'b';
            k--;
            b--;
        }
    }
    print(ans);

    return 0;
}
