#include <bits/stdc++.h>
void Open() {
  freopen(
      "txt"
      ".in",
      "r", stdin);
  freopen(
      "txt"
      ".out",
      "w", stdout);
}
void Close() {
  fclose(stdin);
  fclose(stdout);
}
using namespace std;
int Read() {
  int val = 0, opt = 1;
  char ch;
  while (!isdigit(ch = getchar()))
    if (ch == '-') opt = -1;
  while (isdigit(ch)) (val *= 10) += ch - '0', ch = getchar();
  return val * opt;
}
void work() { printf("%d", (Read() * 3 + Read()) / 2); }
int main(void) {
  work();
  return 0;
}
