test.cs

using System;

public class MyProgram
{
    public static void Main(String[] args)
    {
        int n;
        int[] A = new int[4];
        int[] B = new int[4];
        int[] C = new int[4];
        
        n = 1;
        A[0] = 1;
        A[1] = 4;
        A[2] = 5;
        A[3] = 7;
        B[0] = 2;
        B[1] = 4;
        B[2] = 6;
        B[3] = 7;
        C[0] = 3;
        C[1] = 5;
        C[2] = 6;
        C[3] = 7;
        int i;
        
        for (i = 0 ; i <= 3 ; i += 1)
        {
            if (n == A[i])
            {
                int j;
                Boolean inb;
                
                inb = false;
                j = 0;
                while (j < 4 && inb != true)
                {
                    if (n == B[j])
                    {
                        inb = true;
                    }
                    j = j + 1;
                }
                if (inb == false)
                {
                    inb = false;
                    j = 0;
                    while (j < 4 && inb != true)
                    {
                        if (n == C[j])
                        {
                            inb = true;
                        }
                        j = j + 1;
                    }
                    if (inb == true)
                    {
                        Console.WriteLine("n อยู่ใน A,C แต่ไม่อยู่ใน B");
                    }
                    else
                    {
                        Console.WriteLine("n อยู่ใน A แต่ไม่อยู่ใน Bและ C");
                    }
                }
                else
                {
                    Console.WriteLine("n อยู่ใน A และอยู่ใน B");
                }
            }
        }
    }
}