fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

fn main() {
    let a: usize = read();

    let mut ans = usize::MAX;

    for i in 2..8 {
        let mut r = 0;
        let mut p = 1;
        while p < a {
            r += 1;
            p *= i;
        }
        ans = core::cmp::min(ans, r * i);
    }

    println!("{}", ans);
}