#include <bits/stdc++.h>
using namespace std;
int main() {
  int m, n, a[107][107], c;
  for (m = 0; m <= 100; m++)
    for (n = 0; n <= 100; n++) {
      c = m * 3 + n;
      c = c / 2;
      a[m][n] = c;
    }
  scanf("%d%d", &m, &n);
  printf("%d\n", a[m][n]);
  return 0;
}
