fn main() {
	let mut s = String::new();
	std::io::stdin().read_line(&mut s).ok();
	let n: u64 = s.trim().parse().unwrap();
	let f = |x: u64| {
		let mut i = 1u64;
		while x.pow(i as u32) < n {
			i += 1;
		}
		x * i
	};
	println!("{}", f(2).min(f(3)).min(f(5)))
}