#include<iostream>
#include<cstdio>
#include<algorithm>
#include<fstream>
using namespace std;
string s;
int n,k,dp[1000010][30];
int main()
{
    ifstream cin;
    ofstream cout;
    cin.open("nthword.in");
    cout.open("nthword.out");
    cin>>s;
    int m=s.size();
    cin>>n>>k;
    for(int i=1; i<=m; i++) dp[n][i]=1;
    int sum=0;
    for(int i=n-1; i>=1; i--)
    {
        sum=0;
        for(int j=m; j>=1; j--)
        {
            sum+=dp[i+1][j];
            dp[i][j]=sum;
        }
    }
    int p=1;
    for(int i=1; i<=n; i++)
    {
        for(int j=p; j<=m; j++)
        {
            if(dp[i][j]>k) {p=j; cout<<s[j-1]; break;}
            else {k-=dp[i][j];}
        }
    }
    cout<<endl;
    cin.close();
    cout.close();
    return 0;
}
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