#include <stdio.h>

int main(int argc, char **argv)
{
	int c = 0;
	int num = atoi(argv[1]);
	int i = 0;

	while ((c=getchar()) && c != EOF)
	{	
		if(c == '\n')
			i = -1;
		if(num && i && !(i%num))
			putchar(*argv[2]);
		putchar(c);
		i++;
	}
			

}