import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		long a = sc.nextLong();
		sc.close();

		long ans = a;
		for (int i = 2; i < 64; i++) {
			int r = root(a, i);
			if (power(r, i) < a) {
				r++;
			}
			long val = r * i;
			ans = Math.min(ans, val);
		}
		System.out.println(ans);
	}

	static int root(long x, int n) {
		int ng = 1000000001;
		int ok = 1;
		while (ng - ok > 1) {
			int mid = (ok + ng) / 2;
			if (Math.pow(mid, n) <= Long.MAX_VALUE) {
				ok = mid;
			} else {
				ng = mid;
			}
		}
		ng = ok + 1;
		ok = 1;
		while (ng - ok > 1) {
			int mid = (ok + ng) / 2;
			if (power(mid, n) <= x) {
				ok = mid;
			} else {
				ng = mid;
			}
		}
		return ok;
	}

	static long power(long x, long n) {
		if (n == 0) {
			return 1;
		}
		long val = power(x, n / 2);
		val = val * val;
		if (n % 2 == 1) {
			val = val * x;
		}
		return val;
	}
}