#include<iostream> using namespace std; int main(){ double x,a; cin>>x; if(x<10000){ cout<<"0"; }else if(x>=10000&&x<30000){ a=3; cout<<x/a; }else if(x>=30000&&x<50000){ a=7; cout<<x/a; }else{ a=13; cout<<(x-1000)/a; } return 0; }