#include <stdio.h>

int main (int argc, char ** argv)
{
	int keyLen = 0, index = 0, character = 0;
		
	if (argc != 2)
	{
		fprintf (stderr, "Key Needeed\n");
		return 1;
	}
	
	while (argv[1][keyLen] != '\0') {
		++ keyLen;
	}
	
	while ( (character = fgetc (stdin)) != EOF )
	{
		character ^= argv[1][index];
		fputc (character, stdout);
		
		index = (index + 1) % keyLen;
	}
	
	return 0;
}