import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    }
} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    } main {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int x = sc.nextInt(); x sc.nextInt() sc.nextInt sc double ans = 1; ans 1 for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        } int i = 1; int i = 1; i 1 i < x i x i++ i++ i {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        } {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        } for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            } int j = 2; int j = 2; j 2 j < x j x j++ j++ j {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            } {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            } if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j))); Math.pow(i, j) > x Math.pow(i, j) Math.pow Math i j x break; ans = Math.max(ans, (Math.pow(i, j))) ans Math.max(ans, (Math.pow(i, j))) Math.max Math ans (Math.pow(i, j)) Math.pow Math i j System.out.println((int) ans) System.out.println System.out System System.out (int) ans String[] args args public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    }
} public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int x = sc.nextInt();
        double ans = 1;
        for (int i = 1; i < x; i++) {
            for (int j = 2; j < x; j++) {
                if (Math.pow(i, j) > x)
                    break;
                else
                    ans = Math.max(ans, (Math.pow(i, j)));
            }
        }
        System.out.println((int) ans);
    }
}