#include <bits/stdc++.h>
using namespace std;
int main(void) {
  int a, b, c;
  cin >> a >> b;
  a = a * 3;
  c = a + b;
  if (c % 2 == 0) {
    c = c / 2;
    cout << c;
  } else {
    c = ((c / 2) - 1);
    cout << c;
  }
}
