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.util.*;
import java.math.*;
import static java.lang.System.out;

public class alyona
{
    public static void main(String[] args) throws IOException
    {
        //BufferedReader f = new BufferedReader(new FileReader("/Users/spencersharp/Desktop/input.txt"));
        
        BufferedReader f = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter writer = new PrintWriter(new BufferedOutputStream(System.out));
        
        String output = ""; //Write all output to this string

        //Code here
        String line = f.readLine();
        StringTokenizer st = new StringTokenizer(line);
        long n = Long.parseLong(st.nextToken());
        long m = Long.parseLong(st.nextToken());
        
        long min = Math.min(n,m);
        long max = Math.max(n,m);
        
        n = min;
        m = max;

        long count = 0;
        //How many numbers end in 0 for n
        long num0EndsN = n/10;
        long num0EndsM = m/10;
        
        //How many numbers in 1 for both
        long num1EndsN = (n+9)/10;
        long num1EndsM = (m+9)/10;
        
        //How many numbers in 1 for both
        long num2EndsN = (n+8)/10;
        long num2EndsM = (m+8)/10;
        
        //How many numbers in 1 for both
        long num3EndsN = (n+7)/10;
        long num3EndsM = (m+7)/10;
        
        //How many numbers in 1 for both
        long num4EndsN = (n+6)/10;
        long num4EndsM = (m+6)/10;
        
        //How many numbers in 1 for both
        long num5EndsN = (n+5)/10;
        long num5EndsM = (m+5)/10;
        
        //How many numbers in 1 for both
        long num6EndsN = (n+4)/10;
        long num6EndsM = (m+4)/10;
        
        //How many numbers in 1 for both
        long num7EndsN = (n+3)/10;
        long num7EndsM = (m+3)/10;
        
        //How many numbers in 1 for both
        long num8EndsN = (n+2)/10;
        long num8EndsM = (m+2)/10;
        
        //How many numbers end in 9 for both
        long num9EndsN = (n+1)/10;
        long num9EndsM = (m+1)/10;
        
        
        count += (num0EndsN*num0EndsM) + (num0EndsN*num5EndsM);
        
        count += (num1EndsN*num4EndsM) + (num1EndsN*num9EndsM);
        
        count += (num2EndsN*num3EndsM) + (num2EndsN*num8EndsM);
        
        count += (num3EndsN*num2EndsM) + (num3EndsN*num7EndsM);
        
        count += (num4EndsN*num1EndsM) + (num4EndsN*num6EndsM);
        
        count += (num5EndsN*num0EndsM) + (num5EndsN*num5EndsM);
        
        count += (num6EndsN*num4EndsM) + (num6EndsN*num9EndsM);
        
        count += (num7EndsN*num3EndsM) + (num7EndsN*num8EndsM);
        
        count += (num8EndsN*num2EndsM) + (num8EndsN*num7EndsM);
        
        count += (num9EndsN*num1EndsM) + (num9EndsN*num6EndsM);
        
        output += count;
        
        
        //Code here

        //out.println(output);
        
        writer.println(output);
        writer.close();
        System.exit(0);
        
    }
}
