题意：

思路：

#include <cstdio>
using namespace std;
typedef long long ll;
ll l,r;
ll highbit(ll x){
    ll res = x,cur = x;
    while(cur){
        res = cur;
        cur &= res - 1;
    }
    return res;
}
int main(){
    int t;scanf("%d",&t);
    while(t--){
        scanf("%lld%lld",&l,&r);
        if(l == r) {puts("0");continue;}
        ll x = l^r;
        x = highbit(x);
        printf("%lld\n",(x<<1ll) - 1);
    }
    return 0;
}