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.Map;
import java.util.StringTokenizer;

public class SolutionA {

    private final static String FILENAME;
    private final static String PATH;
    static {
        FILENAME = "";
        if (!FILENAME.isEmpty()) {
            PATH = System.getProperty("user.home") + "/contests/" + FILENAME;
        } else {
            PATH = "";
        }
    }

    public static void main(String[] args) throws IOException {
        SolutionA solution = new SolutionA();
        solution.initInputReader();
        solution.solve();
        solution.cleanup();
    }

    private void solve() throws IOException {
        int n = nextInt(), m = nextInt();
        int small = Math.min(n, m);
        int big = Math.max(n, m);

        int divLeft = small / 5;
        int divRight = big / 5;
        int modLeft = small % 5;
        int modRight = big % 5;

        long ans = 0;
        for (long i = 1; i <= 5; i++) {
            if (i > small)
                break;

            long left = divLeft;
            if (i <= modLeft)
                left++;

            long pair = (5 - i);
            if (pair == 0)
                pair = 5;

            long right = divRight;
            if (pair <= modRight)
                right++;
//            System.out.print(left + " " + right + " ");
//            System.out.println(left * right);
            ans += (left * right);
        }

        System.out.println(ans);
    }

    private final static int MOD = 1000000007;

    /*
     * Methods for reading input
     */

    private BufferedReader br;
    private StringTokenizer st;

    private void initInputReader() throws IOException {
        if (FILENAME.isEmpty()) {
            br = new BufferedReader(new InputStreamReader(System.in));
        } else {
            br = new BufferedReader(new FileReader(new File(PATH)));
        }
        st = new StringTokenizer(br.readLine());
    }

    private void cleanup() throws IOException {
        br.close();
    }

    private int nextInt() throws IOException {
        checkEmptyTokenizer();
        return Integer.parseInt(st.nextToken());
    }

    private long nextLong() throws IOException {
        checkEmptyTokenizer();
        return Long.parseLong(st.nextToken());
    }

    private double nextDouble() throws IOException {
        checkEmptyTokenizer();
        return Double.parseDouble(st.nextToken());
    }

    private String nextString() throws IOException {
        checkEmptyTokenizer();
        return st.nextToken();
    }

    private void checkEmptyTokenizer() throws IOException {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
    }

    /*
     * Convenience methods
     */

    // Provides a default value if map doesn't have the key
    private <K, V> V getFromMap(Map<K, V> map, K key, V def) {
        if (map.containsKey(key)) {
            return map.get(key);
        }
        return def;
    }

    private void print(String line, Object... args) {
        System.out.println(String.format(line, args));
    }
}
