#include<bits/stdc++.h>
	using namespace std;
	#define FAST_IO ios_base::sync_with_stdio(false); cin.tie(NULL)
	#define endl '\n'
	#define ll long long
	#define test_case int t;cin>>t;while(t--)

	 
	    const int mx=2e5+123;
	    long long dp[mx];

	

	int fun(int n){
		
		if(n==0) return 0;
		if(n<0) return 1e9;
		if(dp[n]!=-1) return dp[n];

		int m1,m2;

		m1=fun(n-2)+1;
		m2=fun(n-3)+1;

		dp[n]=min(m1,m2);

		return dp[n];

	}

	

int main(){
	 
			FAST_IO;

			memset(dp,-1,sizeof(dp));

			int n;

			cin>>n;

			cout<<fun(n);



}