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.
import java.io.*;
import java.text.*;
import java.math.*;
import java.util.*;

public class Solution2 
{
	public static void main(String[] args)
	{
		IO inout = new IO();

		long n = inout.lread();
		long m = inout.lread();
		BigInteger count = new BigInteger("0");

		int[] countsn = new int[5];
		int[] countsm = new int[5];

		long index = 1;
		while(index <= n)
		{
			countsn[(int)(index%5)]++;
			index++;
		}

		index = 1;
		while(index <= m)
		{
			countsm[(int)(index%5)]++;
			index++;
		}

		for(int i = 1; i<5; i++)
			count = count.add(new BigInteger(countsm[i]+"").multiply(new BigInteger(""+countsn[5-i])));
		
		//count+=(newcountsm[0]*countsn[0]);
		count = count.add(new BigInteger(countsm[0]+"").multiply(new BigInteger(""+countsn[0])));

		System.out.println(count);
	}

}

class IO
{
	BufferedReader in;
    public IO()
	{
		try 
		{
			in = new BufferedReader(new InputStreamReader(System.in));
			//in = new BufferedReader(new FileReader(taskname + ".in"));

		} 
		catch (Exception e) 
		{
			e.printStackTrace();
			System.exit(1);
		}
	}

	/******************/
	/**********       */
	public int iread()
	{
		try
		{
			return Integer.parseInt(readword());
		}
		catch(Exception e)
		{
			return -1;
		}
		
	}

	/********************/
	/*************      */
	public double dread()
	{
		try	
		{
			return Double.parseDouble(readword());
		}
		catch(Exception e)
		{
			return -1;
		}
	}
	      
	/*******************/
	/***********       */
	public long lread() 
	{
		try
		{
			return Long.parseLong(readword());
		}
		catch(Exception e)
		{
			return -1;
		}
	}
	
	/************************/
	/*************         */
	public String readword()
	{
		StringBuilder b = new StringBuilder();
		int c;
		try
		{
			c = in.read();
			while (c >= 0 && c <= ' ')
				c = in.read();
			if (c < 0)
				return "";
			while (c > ' ') {
				b.append((char) c);
				c = in.read();
			}
			return b.toString();
		}
		catch(Exception e)
		{
			return "";
		}
	}
	
	/************************/
	/*************         */
	public String readLine()
	{
		try
		{
			return in.readLine();
		}
		catch(Exception e)
		{
			return "";
		}
	}
	
	/*************************/
	/***********             */
	public void print(int obj)
	{
		System.out.print(obj);
	}

	/***************************/
	/***********               */
	public void println(int obj)
	{
		System.out.println(obj);
	}
	
	/******************/
	/*****************/
	public void println(String obj)
	{
		System.out.println(obj);
	}
	
	/******************/
	/*****************/
	public void print(String obj)
	{
		System.out.print(obj);
	}
	
	/******************/
	/*****************/
	public void printArray(String[] obj)
	{
		for(String str: obj)
			System.out.println(str);
	}
	
	/******************/
	/*****************/
	public void printArray(int[] obj)
	{
		for(int str: obj)
			System.out.println(str);
	}
	
	/******************/
	/*****************/
	public void printArray(long[] obj)
	{
		for(long str: obj)
			System.out.println(str);
	}

	/**************************/
	public void print(long obj)
	{
		System.out.print(obj);
	}

	/***************************/
	/***********               */
	public void println(long obj)
	{
		System.out.println(obj);
	}

}


