After finishing eating her bun, Alyona came up with two integers n and m. She decided to write down two columns of integers — the first column containing integers from 1 to n and the second containing integers from 1 to m. Now the girl wants to count how many pairs of integers she can choose, one from the first column and the other from the second column, such that their sum is divisible by 5.

Formally, Alyona wants to count the number of pairs of integers (x, y) such that 1 ≤ x ≤ n, 1 ≤ y ≤ m and <image> equals 0.

As usual, Alyona has some troubles and asks you to help.

Input

The only line of the input contains two integers n and m (1 ≤ n, m ≤ 1 000 000).

Output

Print the only integer — the number of pairs of integers (x, y) such that 1 ≤ x ≤ n, 1 ≤ y ≤ m and (x + y) is divisible by 5.

Examples

Input

6 12


Output

14


Input

11 14


Output

31


Input

1 5


Output

1


Input

3 8


Output

5


Input

5 7


Output

7


Input

21 21


Output

88

Note

Following pairs are suitable in the first sample case: 

  * for x = 1 fits y equal to 4 or 9; 
  * for x = 2 fits y equal to 3 or 8; 
  * for x = 3 fits y equal to 2, 7 or 12; 
  * for x = 4 fits y equal to 1, 6 or 11; 
  * for x = 5 fits y equal to 5 or 10; 
  * for x = 6 fits y equal to 4 or 9. 



Only the pair (1, 4) is suitable in the third sample case.
//package codejam;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class AlyonaAndNumbers
{

	public static void main(String[] args) throws Exception
	{
		int n = readInt(), m = readInt();

		long ans = 0;

		for (int i = 1; i <= n; i++)
		{
			int c = 4 - i % 5;

			if (m > c)
				ans += Math.ceil((m - c) / 5.0);
		}

		System.out.println(ans);
	}

	static BufferedReader br = new BufferedReader(new InputStreamReader(
			System.in));
	static PrintWriter out = new PrintWriter(new BufferedWriter(
			new OutputStreamWriter(System.out)));
	static StringTokenizer st;

	static String next() throws IOException
	{
		while (st == null || !st.hasMoreTokens())
			st = new StringTokenizer(br.readLine().trim());
		return st.nextToken();
	}

	static long readLong() throws IOException
	{
		return Long.parseLong(next());
	}

	static int readInt() throws IOException
	{
		return Integer.parseInt(next());
	}

	static double readDouble() throws IOException
	{
		return Double.parseDouble(next());
	}

	static char readChar() throws IOException
	{
		return next().charAt(0);
	}

	static String readLine() throws IOException
	{
		return br.readLine().trim();
	}

}
