fn main() {
    let a: usize = {
        let mut buf = String::new();
        std::io::stdin().read_line(&mut buf).unwrap();
        buf.trim_end().parse().unwrap()
    };

    let mut ans = std::usize::MAX;
    for i in 2..130 {
        let mut res = 0;
        let mut p = 1;
        while p < a {
            res += 1;
            p *= i;
        }
        ans = std::cmp::min(ans, res * i);
    }
    println!("{}", ans);
}