using System;
using System.Collections.Generic;
using static AtCoderer.Exter;
using static System.Console;
using static System.Math;
using System.Linq;

namespace AtCoderer
{

    public class App
    {
        public static void Main(string[] args)
        {
            var n = readarr;
            cout = (n[0] * 3 + n[1])/2
        }
    }
    public static class Exter
    {
        public static void rep(int loop, Action<int> act)
        {
            for (int i = 0; i < loop; i++)
                act(i);
        }
        public static int ToInt(this string v) => int.Parse(v);
        public static int Max(params int[] p) => p.Max();
        public static long Max(params long[] p) => p.Max();
        public static int Min(params int[] p) => p.Min();
        public static long Min(params long[] p) => p.Min();
        public static int Gcd(int a, int b) => a > b ? GcdRecursive(a, b) : GcdRecursive(b, a);
        private static int GcdRecursive(int a, int b) => b == 0 ? a : GcdRecursive(b, a % b);
        public static object cout
        {
            set
            {
                Console.Write(value.ToString());
                Console.WriteLine();

            }
        }
        public static void ToCout<t>(this IEnumerable<t> v)
        {
            cout = string.Join(",", v);
        }
        public static int[] readarr
        {
            get
            {
                return Console.ReadLine().Split().Select(s => int.Parse(s)).ToArray();
            }
        }
        public class UnionFind
        {
            public int[] Parent;
            private int GetRoot(int v)
            {
                if (Parent[v] == v)
                    return v;
                else
                    return Parent[v] = GetRoot(Parent[v]);
            }
            public UnionFind(int size)
            {
                Parent = Enumerable.Range(0, size).ToArray();
            }
            public bool AreGrouped(int a, int b)
            {
                return GetRoot(a) == GetRoot(b);
            }
            public void Connect(int a, int b)
            {
                a = GetRoot(a);
                b = GetRoot(b);
                if (a == b) return;
                else Parent[a] = b;
            }
            public int GetGroupSize(int a)
            {
                return 0;
            }
        }
    }
}
