Problem:
Score : 100 points

Problem Statement

We have A apples and P pieces of apple.

We can cut an apple into three pieces of apple, and make one apple pie by simmering two pieces of apple in a pan.

Find the maximum number of apple pies we can make with what we have now.

Constraints

All values in input are integers.

0 \leq A, P \leq 100

Input

Input is given from Standard Input in the following format:

A P

Output

Print the maximum number of apple pies we can make with what we have.

Sample Input 1

1 3

Sample Output 1

3

We can first make one apple pie by simmering two of the three pieces of apple. Then, we can make two more by simmering the remaining piece and three more pieces obtained by cutting the whole apple.

Sample Input 2

0 1

Sample Output 2

0

We cannot make an apple pie in this case, unfortunately.

Sample Input 3

32 21

Sample Output 3

58

Solution in C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using static System.Math;

namespace Sample
{
    public class Program
    {
        public static void Main(string[] args)
        {
            using (var sc = new SetConsole()) { Solve(); }
        }

        public static void Solve()
        {
            var ap = GetArray<int>();
            var a = ap[0];
            var p = ap[1];
            CWrite((a * 3 + p) / 2);
        }

        static void CWrite<T>(T str) => Console.WriteLine(str);
        static string GetString() => Console.ReadLine();
        static T[] GetArray<T>()
        {
            var str = Console.ReadLine();
            if (str == null) { throw new ArgumentNullException("標準入力がnullです 解答がおかしいはずです"); }

            var t = typeof(T);
            if (t == typeof(string))
            {
                return (T[])(object)str.Split();
            }
            if (t == typeof(int))
            {
                return (T[])(object)str.ToNumArray<T>();
            }
            if (t == typeof(long))
            {
                return (T[])(object)str.ToNumArray<T>();
            }
            if (t == typeof(double))
            {
                return (T[])(object)str.ToNumArray<T>();
            }
            throw new NotSupportedException($"{t} is not supported.");
        }
    }



    class SetConsole : IDisposable
    {
        readonly StreamWriter sw = new StreamWriter(Console.OpenStandardOutput());
        public SetConsole()
        {
            sw.AutoFlush = false;
            Console.SetOut(sw);
        }
        public void Dispose()
        {
            Console.Out.Flush();
            sw.AutoFlush = true;
            Console.SetOut(sw);
        }
    }

    static class ExtentionsLibrary
    {
        public static T[] CopyArray<T>(this T[] array)
        {
            var newArray = new T[array.Length];
            Array.Copy(array, newArray, array.Length);
            return newArray;
        }
        public static T[,] CopyArray<T>(this T[,] array)
        {
            var firstDimentionLength = array.GetLength(0);
            var secondDimentionLength = array.GetLength(1);
            var newDArray = new T[firstDimentionLength, secondDimentionLength];
            Array.Copy(array, newDArray, firstDimentionLength * secondDimentionLength);
            return newDArray;
        }
        public static T[] ToNumArray<T>(this string str)
        {
            var t = typeof(T);
            if (t == typeof(int))
            {
                return (T[])(object)str.Split().Select(int.Parse).ToArray();
            }
            if (t == typeof(long))
            {
                return (T[])(object)str.Split().Select(long.Parse).ToArray();
            }
            if (t == typeof(double))
            {
                return (T[])(object)str.Split().Select(double.Parse).ToArray();
            }
            throw new NotSupportedException();
        }
        public static int ToInt(this string str) => int.Parse(str);
        public static int ToInt(this char chr) => int.Parse(chr.ToString());
        public static long ToLong(this string str) => long.Parse(str);
        public static DateTime ToDateTime(this string str) => DateTime.Parse(str);
    }
}