#include <bits/stdc++.h>
#define fr(i, n, m) for(int i = (n); i < (m); i ++)
#define pb push_back
#define st first
#define nd second
#define pq priority_queue
#define all(x) begin(x), end(x)
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
const int mxn = 1e5;
#include "gap.h"
long long findGap(int T, int N)
{
if(T == 1){
ll lb = 0, rb = (1e18);
vector<ll> v;
fr(i, 0, (int)((N+1)/2)){
ll llb, rrb;
MinMax(lb, rb, &llb, &rrb);
if(llb == -1) break;
v.pb(llb);
v.pb(rrb);
lb = llb+1;
rb = rrb-1;
}
sort(all(v));
ll ans = 0;
fr(i, 0, (int)v.size()-1){
ans = max(ans, v[i+1]-v[i]);
}
return ans;
}
ll a1, an;
MinMax(0, 1e18, &a1, &an);
ll d = (an - a1 + N - 2)/(N-1);
ll pr = a1;
ll ans = d;
for(ll i = 0; a1 + 1 + i*d < an; i++){
ll ai, aj;
MinMax(a1+1 + i*d, min(a1 + (i+1)*d, an-1), &ai, &aj);
if(ai != -1){
ans = max(ans, ai-pr);
pr = aj;
}
}
ans = max(ans, an-pr);
return ans;
}
