#include<stdio.h>
#include <stdlib.h>
#include<strings.h>
#define KSIZE 128

int main(int argc, char **argv) // argv = number of keys
{ int i, j, l;
  char c;  char c2[8];
  char key[KSIZE];
  char buf[KSIZE];

  for(i=0;i<KSIZE;i++) key[i] = 0;
  j = atoi(argv[1]);
  while(j>0)
      { l = 0;  c = 'a';  // l for length;
	printf("input key code, terminate with 0: ");
        while (c != 0) { scanf("%s",c2); c = atoi(c2); buf[l++] = c; }
	for(i=0;i<l;i++) key[i] = key[i] ^ buf[i];
	j--;
      } // while
  printf("The message is: \n  %s\n",key);
 exit(0);
}