import java.util.*;
import java.lang.*;
import java.io.*;
public class GCD
{
public static void main (String[] args) throws java.lang.Exception
{
Scanner scan=new Scanner(System.in);
int a=scan.nextInt(),b=scan.nextInt(),c=scan.nextInt();
int gcd=findgcd(a,b,c);
System.out.println("GCD: "+gcd);
}
static int findgcd(int a,int b,int c)
{
int lim=(a