#define _CRT_SECURE_NO_DEPRECATE
#include <iostream>
#include <string>
#include <vector>
#include <sstream>
#include <ctime>
#include <queue>
#include <algorithm>
#include <iomanip>
#include <map>
#include <set>
#include <math.h>
#include <stack>
#include <deque>
#include <numeric>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <bitset>

#define all(v) v.begin(),v.end()
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
const ld epsylon = 1e-9;
typedef unsigned int ui;
inline long double get_time(){   
	return (long double)clock()/CLOCKS_PER_SEC;
};

string lang;
map <char, int> lng;
map <int, char> lng1;
int n, k;
int sz;
string duma;

void nextt(string & duma)
{
	for (int i = duma.size() - 1; i >= 0; --i)
	{
		if (lng[duma[i]] < sz)
		{
			duma[i] = lng1[lng[duma[i]]+1];
			return;
		} else
		{
			while (lng[duma[i]] >= sz) i--;
			duma[i] = lng1[lng[duma[i]]+1];
			for (int k = i; k < duma.size(); ++k)
				duma[k] = duma[i];
			return;
		}
	}
}

int main()
{
	freopen("nthword.in","r",stdin);
	freopen("nthword.out","w",stdout);
	//program
	cin >> lang;
	sz = lang.size() - 1;
	cin >> k >> n;
	for (int i = 0; i < k - 1; ++i)
		duma.push_back(lang[0]);
	duma.push_back(lang[1]);
	for (int i = 0; i < lang.size(); ++i)
		lng.insert(make_pair(lang[i],i)),
		lng1.insert(make_pair(i, lang[i]));
	for (int i = 0; i < n; ++i)
	{
		nextt(duma);
	}
	cout << duma << endl;
	//end program
	return 0;
}