#include <bits/stdc++.h>
using namespace std;
int n;
typedef long long ll;
void MinMax(ll, ll, ll*, ll*);
ll solve_naive() {
ll l = 0, r = 1000000000000000000LL;
vector<ll> v;
int lim = (n + 1) / 2;
for(int i=1; i<=lim; i++) {
ll x, y;
MinMax(l, r, &x, &y);
v.push_back(x);
if(x != y) v.push_back(y);
l = x + 1;
r = y - 1;
}
sort(v.begin(), v.end());
ll ret = 0;
for(int i=1; i<(ll)v.size(); i++) {
ret = max(ret, v[i] - v[i-1]);
} return ret;
}
ll solve_proway() {
return 0;
}
long long findGap(int32_t T, int32_t N)
{
n = N;
if(T == 1) return solve_naive();
else return solve_proway();
return 0;
}
