import java.util.Scanner;

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

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	}
} import java.util.Scanner; Scanner java.util public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		sc.close();

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	}
} Main public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		sc.close();

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		sc.close();

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc sc.close() sc.close sc int ans = 1; ans 1 for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		} int i = 2; int i = 2; i 2 i * i <= x i * i i i x i++ i++ i {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		} {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		} int b = i; b i while (b <= x) {
				b *= i;
			} b <= x b x {
				b *= i;
			} b *= i b i b /= i b i ans = Math.max(ans, b) ans Math.max(ans, b) Math.max Math ans b System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		sc.close();

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	}
} public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		sc.close();

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	}
} Main
import java.util.Scanner;

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

		int ans = 1;
		for (int i = 2; i * i <= x; i++) {
			int b = i;
			while (b <= x) {
				b *= i;
			}
			b /= i;
			ans = Math.max(ans, b);
		}
		System.out.println(ans);
	}
}
