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)

#pragma region
#include <bits/stdc++.h>
using namespace std;
inline void ci(void){
  return;
}
template <typename First, typename... Rest>
void ci(First& first, Rest&... rest){
  cin >> first;
  ci(rest...);
  return;
}
inline void co(void){
  cout << endl;
  return;
}
template <typename First, typename... Rest>
void co(First first, Rest... rest){
  cout << first << "";
  co(rest...);
  return;
}
#define ll long long
#define ld long double
#define st string
#define wh while
#define ve vector
#define mp make_pair
#define tp tuple
#define mt make_tuple
#define pb push_back
#define pof pop_front
#define pob pop_back
#define pf push_front
#define fr front
#define ft first
#define sc second
#define tos to_string
#define len length
#define rt return
#define br break
#define con continue
#define lcm(n, m) (n * m / __gcd(n, m))
#define np next_permutation
#define repi(i, m, n) for(int i=(int)(m);i<(int)(n);i++)
#define rep(i, n) repi(i, 0, n)
#define revi(i, m, n) for(int i=(int)(m) - 1;i>=(int)(n);i--)
#define rev(i, m) revi(i, m, 0)
#define sz(v) ((int)(v).size()) 
#define each(i, n) for(auto&& i: n)
#define all(n) n.begin(), n.end()
#define allr(n) n.rbegin(), n.rend()
#define sp(n) cout << fixed << setprecision(n)
#define pi 3.14159265358979323846
#define inf 1000000007
#pragma endregion
// sqrt ルート, int 2*10^9, gcd　最大公約数
// __builtin_popcount bitの個数

ve<int> dx = {0, 0, 1, -1}, dy = {1, -1, 0, 0};

int main() {
  int a, p;
  ci(a, p);
  co((a * 3 + p) / 2);
}