# string of alphabets S , T and positive integers N. is given for S , at the end _and T is The operation to add N times. Print the string that has been done


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

ans = []
while n >0:
	g = '_'
	ans.append(s)
	ans.append(g)
	ans.append(t)
	n-=1
	
print(''.join(ans))