/************************************************
Grundlegende Algorithmen mit Java,
http://algorithmen-und-problemloesungen.de/
Copyright @2007-2009 by Doina Logofatu

in C#: Michael Gärtner
************************************************/

using System;
using System.Collections.Generic;
using System.IO;

namespace Logofatu
{
    class P01GGT
    {
        private static String FileInputName = "ggt.in";

        private static int gcd(int a, int b)
        {
            while ( b != 0 )
            {
                int r = a % b;
                a = b;
                b = r;
            }
            return a;
        }

        private static int divide_et_impera(List<int> a, int iMin, int iMax)
        {
            if ( iMin < iMax )
            {
                int middle = (iMin + iMax) / 2;
                int d1 = divide_et_impera(a, iMin, middle);
                int d2 = divide_et_impera(a, middle + 1, iMax);
                return gcd(d1, d2);
            }
            return 0 <= iMin && iMin < a.Count ? a[iMin] : 0;
        }

        static void Main(string[] args)
        {
            List<int> list = new List<int>();
            StreamReader sr = null;
            try
            {
                sr = new StreamReader(FileInputName);
                while ( !sr.EndOfStream )
                {
                    string[] sArray = sr.ReadLine().Split(' ');
                    for ( int i = 0; i < sArray.Length; i++ )
                    {
                        list.Add(int.Parse(sArray[i]));
                    }
                }
                int sz = list.Count;
                if ( sz > 0 )
                {
                    Console.WriteLine(" ggT = " + divide_et_impera(list, 0, sz - 1));                   
                }
            }
            catch ( IOException ex )
            {
                Console.WriteLine("Fehler bei der Dateiverarbeitung!\n" + ex);
            }
            finally
            {
                if ( sr != null )
                {
                    sr.Close();
                }
            }
        }
    }
}