#include<stdio.h>
char s[100005], t[100005];
int main()
{
	int i, j, n;
	scanf("%s%s%d", s, t, &n);
	int ss;
	for (ss = 0; s[ss] != '\0'; ss++);
	for (j = 0; j < n; j++)
	{
		s[ss] = '_';
		ss++;
		for (i = 0; t[i] != '\0'; i++)
		{
			s[ss] = t[i];
			ss++;
		}
		s[ss] = '\0';
	}
	printf("%s\n", s);
	return 0;
}