#include "gap.h"
#include <bits/stdc++.h>
using namespace std;
const long long nmax=1e5+42,inf=1e18+42;
int n;
long long inp[nmax];
/*
void MinMax(long long low,long long up,long long &a,long long &b)
{
cout<<low<<" "<<up<<endl;
cin>>a;
cin>>b;
}
*/
void ask(long long low,long long up,long long &mini,long long &maxi)
{
MinMax(low,up,&mini,&maxi);
}
long long findGap(int T,int N)
{
n=N;
long long mini,maxi;
ask(0,inf,mini,maxi);
//cout<<"mini= "<<mini<<" maxi= "<<maxi<<endl;
inp[1]=mini;
inp[n]=maxi;
for(int le=2;le<=n+1-le;le++)
{
int ri=n+1-le;
ask(inp[le-1]+1,inp[ri+1]-1,mini,maxi);
inp[le]=mini;
inp[ri]=maxi;
}
long long ret=0;
for(int i=2;i<=n;i++)
ret=max(ret,inp[i]-inp[i-1]);
return ret;
}
/*
int main()
{
cout<<findGap(1,4)<<endl;
}
*/
