use proconio::input;
use std::collections::HashMap;
use std::collections::BTreeSet;
use std::ops::ControlFlow::Break;
fn main(){
    input!{
        n:usize,
    }
    let mut ans=0;
    if n%2==1{
        ans=1;
    } else {
        ans=n/2;
    }
    print!("{}",ans);
}