#include<bits/stdc++.h>
using namespace std;
int read(){
	char c=getchar();
	int sum=0,flag=1;
	while(c<'0'||c>'9'){
		if(c=='-') flag=(~flag)+1;
		c=getchar();
	}
	while(c>='0'&&c<='9') sum=(sum<<1)+(sum<<3)+c-'0',c=getchar();
	return sum*flag;
}
void write(int x){
	if(x<0) x=(~x)+1,putchar('-');
	if(x>9) write(x/10);
	putchar(x%10+'0');
}
int add(int x,int y){
	if(!(x&y)) return x^y;
	int tem=(x&y)<<1;
	return add(tem,x^y);
}
int x=read(),y=read();
int main(){
	write(add(x,y));
	return 0;
}