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
import java.util.Scanner;
 
class Main {
    public static void main(String args[]){
	Scanner sc = new Scanner(System.in);
	int a,p,maxap;
 
	a = sc.nextInt();
	p = sc.nextInt();
 
	maxap = (3*a + p) /2;
 
	System.out.println(maxap);
    }
}