#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int apple = 0;
  int apple_block = 0;
  int apple_pie = 0;
  cin >> apple;
  cin >> apple_block;
  apple_pie = ((3 * apple) + apple_block) / 2;
  cout << apple_pie << endl;
  return apple_pie;
}
