Problem:
Score : 100 points

Problem Statement

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.

Sample Input 1

1 3

Sample Output 1

3

We can first make one apple pie by simmering two of the three pieces of apple. Then, we can make two more by simmering the remaining piece and three more pieces obtained by cutting the whole apple.

Sample Input 2

0 1

Sample Output 2

0

We cannot make an apple pie in this case, unfortunately.

Sample Input 3

32 21

Sample Output 3

58

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

//AUTHOR:BlackBox Inc.//
#include<bits/stdc++.h>
#include<unordered_map>
#include<tr1/unordered_map>
#define ll long long
#define ull unsigned long long
#define vi vector<int>
#define vlli vector<long long int>
#define vvi vector<vector<int>>
#define endl "\n"
#define vpii vector<pair<int,int>>
#define vs vector<string>
#define lin1(x) ll int x; x = scan();
#define lin2(x,y) ll int x, y; x = scan(), y = scan();
#define lin3(x,y,z) ll int x, y, z; x = scan(), y = scan(), z = scan();
#define pb(x) push_back(x)
#define makep(x,y) make_pair(x,y)
#define mx(a,b) (a)>(b)?(a):(b)
#define mn(a,b) (a)<(b)?(a):(b)
#define fori(s,e) for(i=s;i<=e;i++)
#define forj(s,e) for(j=s;j<=e;j++)
#define fork(s,e) for(k=s;k<=e;k++)
#define rep(i,s,e) for(int i=s;i<=e;i++)
#define brep(i,s,e) for(int i=s;i>=e;i--)
#define all(x) x.begin(),x.end()
#define mem(x,y) memset(x,y,sizeof(x));
#define bits1(x) __builtin_popcount(x)
#define pi 3.14159265358979323846264338327950
#define MOD7 1000000007
#define MOD9 1000000009
#define fast std::ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
using namespace std;
using namespace std::tr1;

int main()
{
#ifdef RAHUL
    freopen("input.txt","r",stdin);
#endif


int a,b;
cin>>a>>b;

	int max=a*3+b;
	cout<<max/2<<endl;

	return 0;
}