Problem: You are given two integers n and k. Find k-th smallest divisor of n, or report that it doesn't exist.

Divisor of n is any such natural number, that n can be divided by it without remainder.

Input

The first line contains two integers n and k (1 ≤ n ≤ 1015, 1 ≤ k ≤ 109).

Output

If n has less than k divisors, output -1.

Otherwise, output the k-th smallest divisor of n.

Examples

Input

4 2


Output

2


Input

5 3


Output

-1


Input

12 5


Output

6

Note

In the first example, number 4 has three divisors: 1, 2 and 4. The second one is 2.

In the second example, number 5 has only two divisors: 1 and 5. The third divisor doesn't exist, so the answer is -1.

Solution (in JAVA):

Solution:
/*
 * Code Author: Akshay Miterani
 * DA-IICT
 */
import java.io.*;
import java.math.*;
import java.util.*;

public class Main {

	InputReader in;
	PrintWriter out;
	Main() throws IOException {
		in = new InputReader(System.in);
		out = new PrintWriter(System.out);
		//in = new InputReader(new FileInputStream("input_.txt"));
		//out = new PrintWriter(new File("output_.txt"));
		solve();
		out.close();
	}

	public static void main(String args[]) {
		new Thread(null, new Runnable() {
			public void run() {
				try {
					new Main();
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}, "1", 1 << 26).start();
	}

	//--------------------My Code Starts Here----------------------
	long mod=(long)1e9+9;
	double eps=1e-150;
	public void solve() throws IOException{
		long n=in.nextLong();
		long k=in.nextLong();
		ArrayList<Long> arr=new ArrayList<>();
		for(long i=1;i*i<=n;i++){
			if(n%i==0){
				arr.add(i);
				if(i*i!=n)
					arr.add(n/i);
			}
		}
		Collections.sort(arr);
		if(k>arr.size())
			out.println("-1");
		else{
			out.println(arr.get((int)(k-1)));
		}
	}
	//---------------------My Code Ends Here------------------------
	
	static long modulo(long a,long b,long c) {
		long x=1;
		long y=a;
		while(b > 0){
			if(b%2 == 1){
				x=(x*y)%c;
			}
			y = (y*y)%c; // squaring the base
			b /= 2;
		}
		return  x%c;
	}
	static class Pair implements Comparable<Pair>{
		int x;
		int y;
		Pair(int xx,int yy){
			x=xx;
			y=yy;
		}
		@Override
		public int compareTo(Pair o) {
			if(Long.compare(this.x, o.x)!=0)
				return Long.compare(this.x, o.x);
			else
				return Long.compare(this.y, o.y);
		}
	}
	public static void debug(Object... o) {
		System.out.println(Arrays.deepToString(o));
	}

	static final class InputReader{
		private final InputStream stream;
		private final byte[] buf=new byte[1024];
		private int curChar;
		private int numChars;
		public InputReader(InputStream stream){this.stream=stream;}
		private int read()throws IOException{
			if(curChar>=numChars){
				curChar=0;
				numChars=stream.read(buf);
				if(numChars<=0)
					return -1;
			}
			return buf[curChar++];
		}
		public final int nextInt()throws IOException{return (int)nextLong();}
		public final long nextLong()throws IOException{
			int c=read();
			while(isSpaceChar(c)){
				c=read();
				if(c==-1) throw new IOException();
			}
			boolean negative=false;
			if(c=='-'){
				negative=true;
				c=read();
			}
			long res=0;
			do{
				if(c<'0'||c>'9')throw new InputMismatchException();
				res*=10;
				res+=(c-'0');
				c=read();
			}while(!isSpaceChar(c));
			return negative?(-res):(res);
		}
		public final int[] readIntBrray(int size)throws IOException{
			int[] arr=new int[size];
			for(int i=0;i<size;i++)arr[i]=nextInt();
			return arr;
		}
		public final String next()throws IOException{
			int c=read();
			while(isSpaceChar(c))c=read();
			StringBuilder res=new StringBuilder();
			do{
				res.append((char)c);
				c=read();
			}while(!isSpaceChar(c));
			return res.toString();
		}
		public final String nextLine()throws IOException{
			int c=read();
			while(isSpaceChar(c))c=read();
			StringBuilder res=new StringBuilder();
			do{
				res.append((char)c);
				c=read();
			}while(c!='\n'&&c!=-1);
			return res.toString();
		}
		private boolean isSpaceChar(int c){
			return c==' '||c=='\n'||c=='\r'||c=='\t'||c==-1;
		}
	}
}