#include
using namespace std;
int main(int argc, char** argv){
int a,b;
cin>>a;
b=a%3;
a=a/3+1-(b==0);
cout<<a;
}
#include
using namespace std;
int main() {
int n;
cin >> n;
cout << (n - 1) / 3 + 1;
}
#include<iostream>
#include<iomanip>
using namespace std;
int main(){
double a;
cin >> a;
cout << fixed << setprecision(0) << a / 3 + 0.4;
}