p03029 AtCoder Beginner Contest 128 - Apple Pie
We have A apples and P pieces of apple.

We can cut an apple into three pieces of apple, and make one apple pie by simmering two pieces of apple in a pan.

Find the maximum number of apple pies we can make with what we have now.

Constraints

* All values in input are integers.
* 0 \leq A, P \leq 100

Input

Input is given from Standard Input in the following format:


A P


Output

Print the maximum number of apple pies we can make with what we have.

Examples

Input

1 3


Output

3


Input

0 1


Output

0


Input

32 21


Output

58
```python
A, P = map(int, input().split())

print(((A*3)+P)//2)
```