傳送門

#include <bits/stdc++.h>
typedef long long ll;
ll l,r,mid;
int t;
int main(){
	scanf("%lld%lld",&l,&r);
	if (l==r){
		puts("1");
		return 0;
	}
	for (int i=60;i>=0;i--)
		if ((l&(1ll<<i))==(r&(1ll<<i)))
			l-=(l&(1ll<<i)),r-=(r&(1ll<<i));
		else {
			mid=1ll<<i;
			t=-1;
			for (int j=i-1;j>=0;j--) 
				if (r&(1ll<<j)){
					t=j;
					break;
				}
			break;
		}
	ll l1=l,r1=(t==-1)?mid:mid+(1ll<<t+1)-1;
	ll l2=mid|l,r2=2*mid-1;
	if (l2<=r1) printf("%lld\n",r2-l1+1);
	else printf("%lld\n",r1-l1+1+r2-l2+1);
}