using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static void Main(string[] args)
    {
        var A = sc.ReadInt();
        var B = sc.ReadInt();
        var C = sc.ReadInt();
        var K = sc.ReadInt();

        var ans = A + B + C;
        var max = Math.Max(A, Math.Max(B, C));
        for (int i = 0; i < K; i++)
        {
            ans += max;
            max *= 2;
        }
        Console.WriteLine(ans);
    }
    static Scanner sc = new Scanner();
}

class Scanner
{
    string[] S = new string[0];
    int Index = 0;
    char[] Separators = new char[] { ' ' };

    public string Next()
    {
        if (this.Index < this.S.Length) return this.S[this.Index++];
        var line = "";
        while (line == "") line = Console.ReadLine();
        this.S = line.Split(this.Separators, StringSplitOptions.RemoveEmptyEntries);
        if (this.S.Length == 0) return this.Next();
        this.Index = 0;
        return this.S[this.Index++];
    }
    public string ReadStr()
    {
        return this.Next();
    }
    public char ReadChar()
    {
        return this.Next()[0];
    }
    public int ReadInt()
    {
        return int.Parse(this.Next());
    }
    public uint ReadUInt()
    {
        return uint.Parse(this.Next());
    }
    public long ReadLong()
    {
        return long.Parse(this.Next());
    }
    public double ReadDouble()
    {
        return double.Parse(this.Next());
    }
    public Tuple<int, int> ReadTup_int2()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt());
    }
    public Tuple<int, int, int> ReadTup_int3()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt(), this.ReadInt());
    }
    public Tuple<int, int, int, int> ReadTup_int4()
    {
        return Tuple.Create(this.ReadInt(), this.ReadInt(), this.ReadInt(), this.ReadInt());
    }
    public int[] ReadIntArray(int n)
    {
        var array = new int[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadInt();
        }
        return array;
    }
    public long[] ReadLongArray(int n)
    {
        var array = new long[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadLong();
        }
        return array;
    }
    public double[] ReadDoubleArray(int n)
    {
        var array = new double[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadDouble();
        }
        return array;
    }
    public char[] ReadCharArray(int n)
    {
        var array = new char[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadChar();
        }
        return array;
    }
    public string[] ReadStrArray(int n)
    {
        var array = new string[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadStr();
        }
        return array;
    }
    public Tuple<int, int>[] ReadTupArray_int2(int n)
    {
        var array = new Tuple<int, int>[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadTup_int2();
        }
        return array;
    }
    public Tuple<int, int, int>[] ReadTupArray_int3(int n)
    {
        var array = new Tuple<int, int, int>[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadTup_int3();
        }
        return array;
    }
    public Tuple<int, int, int, int>[] ReadTupArray_int4(int n)
    {
        var array = new Tuple<int, int, int, int>[n];
        for (int i = 0; i < array.Length; i++)
        {
            array[i] = this.ReadTup_int4();
        }
        return array;
    }
}


Measured memory_bytes: 13140