const INF: usize = 1usize << 60;

fn main() {
    let mut n = String::new();
    std::io::stdin().read_line(&mut n).ok();
    let n: usize = n.trim().parse().unwrap();

    let mut dp = vec![INF; n+1];
    dp[1] = 0;
    for i in 1..n {
        for j in 2..=n/i {
            let idx = i*j;
            if idx > n { break; }
            dp[idx] = dp[idx].min(dp[i] + j);
        }
    }
    println!("{}", dp[n]);
}