using System;

using System.Collections.Generic;       

public class Program

{

    public static void Main()

    {

        int[] array1 = new int[]{0,0,0};

        int[] array2 = new int[]{0,2,2,4,5,6,7};

        var dictionary1 = new Dictionary<int, int>();

        int minNumber = int.MaxValue;

        for(var i = 0; i < array1.Length; i++)

        {

            if(!dictionary1.ContainsKey(array1[i]))

            {

                dictionary1.Add(array1[i],1);

            }

        }

        for(var i = 0; i < array2.Length; i++)

        {

            if(dictionary1.ContainsKey(array2[i]) && array2[i] < minNumber)

            {

                minNumber = array2[i];

            }

        }

        Console.WriteLine("smallest common number is {0}", minNumber);

    }

}