import sys


def main():
    sys.setrecursionlimit(100000)
    input = lambda: sys.stdin.readline()[:-1]
    S = input()
    T = input()
    N = int(input())

    ans = [S] + [T] * N
    print(*ans, sep="_")


if not __debug__:
    f = open(sys.argv[1], "r")
    sys.stdin = f

try:
    sys.set_int_max_str_digits(100000)
except AttributeError:
    pass

main()