/*4 4 5 3 1+2 6 2 7 3 2+1 8 4 2+2 9 3 10 4 3+1 11 5 3+2;*/ #include<iostream> using namespace std; int main(){ int n; cin>>n; if(n==4) cout<<4; else if(n%3==0) cout<<n/3; else cout<<n/3+n%3; return 0; }