> #include<stdio.h>
> #include<string.h>
> unsigned char space[20100],nospace[20100];
> int main()
> {
> 	int len,i;
> 	unsigned char key,clear;
> 	//freopen("in.txt","r",stdin);
> 	scanf("%s",nospace);
> 	scanf("%s",space);
> 	len=strlen(nospace);
> 	for(i=0;i<=len-1;i++)
> 	{
> 		if (nospace[i]>='0'&&nospace[i]<='9')
> 			nospace[i]-='0';
> 		else nospace[i]=nospace[i]-('A'-10);
> 	}
> 	for(i=0;i<=len-1+2;i++)
> 	{
> 		if (space[i]>='0'&&space[i]<='9')
> 			space[i]-='0';
> 		else space[i]=space[i]-('A'-10);
> 	}
> 	len/=2;
> 	for(i=0;i<=len-1;i++)
> 		nospace[i]=nospace[i*2]*16+nospace[i*2+1];
> 	for(i=0;i<=len;i++)
> 		space[i]=space[i*2]*16+space[i*2+1];
> 	clear=' ';
> 	for(i=0;i<=len-1;i++)
> 	{
> 		key=space[i]^clear;
> 		clear=nospace[i]^key;
> 		printf("%02X",(int)key);
> 	}
> 	key=space[i]^clear;
> 	printf("%02X\n",key);
> 	return 0;
> }