#include<stdio.h>
#include<stdlib.h>
int main()
{
long a,b;
while(scanf("%ld%ld",&a,&b)==2)
{
long c=a^b;
printf("%ld\n",c);
}
system("PAUSE");
}
/*
wrong
#include<stdio.h>
#include<stdlib.h>
int main()
{
unsigned long a,b,c;
while(scanf("%uld%uld",&a,&b)==2)
{
c=a^b;
printf("%uld\n",c);
}
system("PAUSE");
}
*/
