#P682A. Alyona and Numbers

    ID: 3557 Type: RemoteJudge 1000ms 256MiB Tried: 0 Accepted: 0 Difficulty: (None) Uploaded By: Tags>constructive algorithmsmathnumber theory*1100

Alyona and Numbers

No submission language available for this problem.

Description

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 equals 0.

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

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

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.

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.

Samples

6 12

14

11 14

31

1 5

1

3 8

5

5 7

7

21 21

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.