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

void solve(){
    int n;
    cin>>n;
    if(n%3 == 0){
    	cout<<n/3<<"\n";
    	return;
    }
    else if(n%3 == 1){
    	cout<<(n-3)/3 + 2<<"\n";
    	return;
    }
    cout<<(n/3)+1<<"\n";
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    int test = 1;
    // cin>>test;
    while(test--)
        solve();
}