#19344: 嘿嘿嘿
#include <iostream>
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 <iostream>
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;
}