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.*;

public class Round357_div2_A {

    static final long MOD = 1_000_000_007L; // distributive over + - * (NOT /)

    public static void main(String[] args) throws IOException {
        FastReader in = new FastReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
        solve(in, out);
    }


    public static void solve(FastReader in, PrintWriter out) {
        int nn = in.readInt();
        int mm = in.readInt();

        int n = Math.min(nn, mm);
        int m = Math.max(nn, mm);

        long solution = 0;
        for (int sum = 5 ; sum <= n + m ; sum += 5) {
            if (n >= sum - 1 && m >= sum - 1) {
                solution += sum - 1;
            } else if (m >= sum - 1) {
                solution += n;
            } else {
                solution += Math.min((m + n) - sum + 1, sum - 1);
            }
        }

        out.println(solution);
        out.flush();
    }


    /**
     * Custom buffered reader. Faster than Scanner and BufferedReader + StringTokenizer.
     */
    static class FastReader {
        private final InputStream stream;
        private int current;
        private int size;
        private byte[] buffer = new byte[1024 * 8];

        public FastReader(InputStream stream) {
            this.stream = stream;
            current = 0;
            size = 0;
        }

        public int readInt() {
            int sign = 1;
            int abs = 0;
            int c = readNonEmpty();
            if (c == '-') {
                sign = -1;
                c = readAny();
            }
            do {
                if (c < '0' || c > '9') {
                    throw new IllegalStateException();
                }
                abs = 10 * abs + (c - '0');
                c = readAny();
            } while (!isEmpty(c));
            return sign * abs;
        }

        public int[] readIntArray(int n) {
            int[] array = new int[n];
            for (int i = 0 ; i < n ; i++) {
                array[i] = readInt();
            }
            return array;
        }

        public char readChar() {
            return (char) readNonEmpty();
        }

        public String readString() {
            StringBuffer sb = new StringBuffer();
            int c;
            do {
                c = readAny();
            } while (isEmpty(c));
            do {
                sb.append((char) c);
                c = readAny();
            } while (!isEmpty(c));
            return sb.toString();
        }

        private int readAny() {
            try {
                if (current >= size) {
                    current = 0;
                    size = stream.read(buffer);
                    if (size < 0) {
                        return -1;
                    }
                }
            } catch (IOException e) {
                throw new RuntimeException("Failed to readAny next byte", e);
            }
            return buffer[current++];
        }

        private int readNonEmpty() {
            int result;
            do {
                result = readAny();
            } while (isEmpty(result));
            return result;
        }

        private static boolean isEmpty(int c) {
            return c == ' ' || c == '\t' || c == '\n' || c == '\r' || c == -1;
        }
    }
}
