/* -*- coding: utf-8 -*-
 *
 * 2399.cc:  No.2399 This Is Truly Final Edition - yukicoder
 */

#include<cstdio>
#include<algorithm>
 
using namespace std;

/* constant */

const int MAX_L = 10;

/* typedef */

/* global variables */

char s[MAX_L + 4], t[MAX_L + 4];

/* subroutines */

/* main */

int main() {
  int n;
  scanf("%s%s%d", s, t, &n);

  printf("%s", s);
  for (int i = 0; i < n; i++)
    printf("_%s", t);
  putchar('\n');

  return 0;
}