p00352 Handsel
Alice and Brown are brothers in a family and each receives pocket money in celebration of the coming year. They are very close and share the total amount of the money fifty-fifty. The pocket money each receives is a multiple of 1,000 yen.

Write a program to calculate each one’s share given the amount of money Alice and Brown received.



Input

The input is given in the following format.


a b


A line of data is given that contains two values of money: a (1000 ≤ a ≤ 50000) for Alice and b (1000 ≤ b ≤ 50000) for Brown.

Output

Output the amount of money each of Alice and Brown receive in a line.

Examples

Input

1000 3000


Output

2000


Input

5000 5000


Output

5000


Input

1000 2000


Output

1500
```python
a, b = map(int, input().split())
cash = (a+b)//2
print(cash)

```