using System;

public class Program

{

int max(int A, int B, int C)

{

    return Math.Max(A, Math.Max(B,C));

}

​

public void Main()

{

    var e = new byte[] {5,6,1,4,9,3,1,2};

    var i=0;

    var j = e.Length-1;

    int A = e[i];

    int C = e[j];

    int B = 0;

    for(int x = i+1 ; x < j; x++) B+=e[x];

    var mp = int.MaxValue;

    var m = max(A,B,C);

    Console.WriteLine("A={0} B={1} C={2}", A, B, C);

    while(m < mp)

    {

        int AL = A+e[i+1];

        int CR = C+e[j-1];

        int BL = B-e[i+1];

        int BR = B-e[j-1];

        if(max(AL,BL,C) < max(A,BR,CR) )

        {

            A=AL;

            B=BL;

            i++;

        }

        else

        {

            C=CR;

            B=BR;

            j--;

        }

        mp = m;

        m = max(A,B,C);

        Console.WriteLine("A={0} B={1} C={2}  MAX={3}", A, B, C, m);

    }

    Console.WriteLine(mp);

}

}