#include<bits/stdc++.h>
#define int long long
using namespace std;
int nCr(int i,int j){
  int sum=1;
  for(int X=1;X<=j;X++){
    sum*=(i-X+1);sum/=X;
  }
  return sum;
}
signed main(){
  int A,B,K;cin>>A>>B>>K;
  int now=K;
  int NA=A,NB=B;
  string S="";
  for(int X=0;X<A+B;X++){
    if(now>nCr(NA+NB-1,NB)){
      now-=nCr(NA+NB-1,NB);
      NB--;
      S.push_back('b');
    }
    else{
      NA--;
      S.push_back('a');
    }
  }
  cout<<S<<endl;
}
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0; i<(int)n; ++i)
using ll=long long;

vector<vector<ll>> c;

string kth(int a,int b,ll k) {
    if(a==0) return string(b, 'b');
    if(b==0) return string(a, 'a');
    if(k<=c[a-1][b]) return string("a")+kth(a-1,b,k);
    else return string("b")+kth(a, b-1, k-c[a-1][b]);
}

int main() {
  int a,b; ll k; cin >> a >> b >> k;
  c.resize(a+1, vector<ll>(b+1));
  c[0][0]=1; 
  rep(i,a+1) rep(j,b+1) { if(i>0) c[i][j]+=c[i-1][j]; if(j>0) c[i][j]+=c[i][j-1]; }
  cout << kth(a,b,k) << endl;
}