#include<iostream> // cin\cout\endl using namespace std; int main(){ int s1=10000,s2=10000,n; cin>>n; for(int i=0;i<(n-1)/2;i++){ s1=s1-1; s2=s2-2; } if(n%2==0) cout<<s2<<endl; else cout<<s1<<endl; return 0; }