#include <iostream>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <cmath>
using namespace std;

long long a[105][105], k, b[105];
int n, m;
string st;

int main()
{
    for (int i = 1; i <= 60; i++) {a[0][i] = 1; a[i][0] = 1;}
    for (int i = 1; i <= 60; i++)
        for (int j = 1; j <= i; j++)
        {
            a[i][j] = a[i - 1][j] + a[i - 1][j - 1];
           // cout << a[i][j] << endl;
        }
    cin >> n >> m;
    cin >> k;
    int i = m, cntm = m;
    long long cnt = k;

    while (cntm)
    {
        if (a[i][cntm] > cnt)
            {
                b[n + m - i + 1] = 1;
                cnt -= a[i - 1][cntm];
                i = cntm - 2;
                cntm--;
                //cout <<i << 'c';
            }
        else if (a[i][cntm] == cnt)
        {
            int x = n + m - i + 1;
           // cout << cntm << ' ' << cnt << ' ' << i;
            for (int j = x; j <= x + cntm - 1; j++)
                b[j] = 1;
            for (int j = 1; j <= n + m; j++)
                if (b[j]) cout <<'b'; else cout << 'a';
                cout << endl;
            return 0;
        }
        i++;
    }
    for (int j = 1; j <= n + m; j++)
        if (b[j]) cout <<'b'; else cout << 'a';
        cout << endl;
    return 0;
}

#include "bits/stdc++.h"
using namespace std;

long long ncr(long long a,long long b)
{
    long long m=1;
    for(int i=a;i>b;i--)
    {
        m*=i;
        m/=a-i+1;
    }
    return m;
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    long long a = 0, b = 0, c = 0, d = 0, e = 0, f = 0, m = 0, n = 0, p = 0, q = 0, mod = 1000000007, pi = 3.1415926535;
    string s1, s2;
    char moji;

   cin >> a >> b >> c;
   d=a+b;
   c--;
   for(int i=0;i<d;i++)
   {
       if(ncr(a+b-1,max(a-1,b))<=c)
       {
           c-=ncr(a+b-1,max(a-1,b));
           cout << 'b';
           b--;
       }
       else
       {
           if(a)
           {
               cout << 'a';
             a--;
           }
           else
           {
              cout << 'b';
             b--;
           }
       }
   }
   cout << endl;
    return 0;
}