import java.io.*;
import java.util.*;
import java.lang.*;
public class RookieVirus
{
    public static void main(String[] args)
    {
        Scanner scan=new Scanner(System.in);
        double a=scan.nextDouble();
        double b=scan.nextDouble();
        double t=scan.nextDouble();   //in millis
        double power=Math.pow(10.00,9.00);
        
        int power1=(int)power;
      
        double virus=0.5*a*t+0.5*b*t;
        
        long virus1=(long)virus;
        
        long output=3%power1;
        
        System.out.println(output);
    }
}