#include "gap.h"
#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll mn,mx;
ll l,r,mid;
ll a[100005];
int h,t;
ll ans;
unsigned long long now,pre;
unsigned long long len;
long long findGap(int T, int N)
{
if (T==1) {
h=0,t=N+1;
l=0,r=1e18+1;
for (;;) {
MinMax(l,r,&mn,&mx);
a[++h]=mn,a[--t]=mx;
l=mn+1,r=mx-1;
if (h>=t-1) break;
}
for (int i=1;i<=N-1;i++) {
ll t=a[i+1]-a[i];
if (t>ans) ans=t;
}
printf("%lld\n",ans);
} else {
MinMax(0,1e18+1,&mn,&mx);
now=mn;
len=1;
pre=now;
while (now<=1e18) {
MinMax(now+1,now+len,&mn,&mx);
if (mn==-1) {
now+=len;
len*=2;
} else {
ans=max(ans,mn-(ll)pre);
now=mx;
}
}
printf("%lld\n",ans);
}
return 0;
}
