import sys
sys.setrecursionlimit(5*10**5)
input = sys.stdin.readline
from collections import defaultdict, deque, Counter
from heapq import heappop, heappush
from bisect import bisect_left, bisect_right
from math import gcd

s = input().rstrip()
t = input().rstrip()
n = int(input())

for i in range(n):
    s += "_"
    s += t

print(s)