#include <bits/stdc++.h>
typedef long long ll;
using namespace std;

const int INF = 1e9;
const int MOD = 1e9+7;
const ll LINF = 1e18;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) for(int i=0;i<(n);++i)
#define REPR(i,n) for(int i=n;i>=0;i--)
#define ALL(v) (v.begin(),v.end())
#define COUT(x) cout<<(x)<<"\n"

ll gcd(ll x,ll y){
  if(y==0)return x;
  if(x<=y) swap(x,y);
  if(x%y==0) return y;
  else return(gcd(y,x%y));//最大公約数
}

int main(){
    ll n;cin >> n;
    ll num = (1/2.0)*n*(n-1);
    COUT(gcd(n,num));
    return 0;
}