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.IO;

namespace Sandbox
{
    class Program
    {
        static void Main(string[] args)
        {
            var scanner = new Scanner();
            var a = scanner.GetNextAsInt();
            var p = scanner.GetNextAsInt();

            p += a * 3;

            Console.WriteLine(p / 2);
        }
    }

    #region String Scanner
    public class Scanner
    {
        private const char Separator = ' ';
        private readonly StreamReader _Stream = new StreamReader(Console.OpenStandardInput());
        private int _Pos;
        private string[] _Line = new string[0];

        #region get a element
        public string GetNext()
        {
            // ReSharper disable once InvertIf
            if (this._Pos >= this._Line.Length)
            {
                // ReSharper disable once PossibleNullReferenceException
                this._Line = this._Stream.ReadLine().Split(Separator);
                this._Pos = 0;
            }
            return this._Line[this._Pos++];
        }
        public int GetNextAsInt()
        {
            return int.Parse(this.GetNext());
        }
        public long GetNextAsLong()
        {
            return long.Parse(this.GetNext());
        }
        public double GetNextAsDouble()
        {
            return double.Parse(this.GetNext());
        }
        #endregion

        #region get array
        public string[] ToArrayFromNextLine()
        {
            if (this._Pos >= this._Line.Length)
            {
                // ReSharper disable once PossibleNullReferenceException
                this._Line = this._Stream.ReadLine().Split(Separator);
            }

            this._Pos = this._Line.Length;
            return this._Line;
        }
        public int[] ToIntArrayFromNextLine()
        {
            return ToIntArray(this.ToArrayFromNextLine());
        }
        public long[] ToLongArrayFromNextLine()
        {
            return ToLongArray(this.ToArrayFromNextLine());
        }
        public double[] ToDoubleArrayFromNextLine()
        {
            return ToDoubleArray(this.ToArrayFromNextLine());
        }
        #endregion

        #region convert array
        private static int[] ToIntArray(string[] array)
        {
            var result = new int[array.Length];
            for (var i = 0; i < array.Length; i++)
            {
                result[i] = int.Parse(array[i]);
            }
            return result;
        }
        private static long[] ToLongArray(string[] array)
        {
            var result = new long[array.Length];
            for (var i = 0; i < array.Length; i++)
            {
                result[i] = long.Parse(array[i]);
            }
            return result;
        }
        private static double[] ToDoubleArray(string[] array)
        {
            var result = new double[array.Length];
            for (var i = 0; i < array.Length; i++)
            {
                result[i] = double.Parse(array[i]);
            }
            return result;
        }
        #endregion
    }
    #endregion
}