import java.util.Scanner;

public class Main{
    public static void print(String a){
        System.out.println(a);
    }
    public static void print(int a){
        System.out.println(a);
    }
    public static void print(long a){
        System.out.println(a);
    }
    public static int  pow(int a,int b){
        int res=1;
        while (b>0){
            if (b%2==1){
                res*=a;
            }
            a*=a;b>>=1;
        }
        return res;
    }
    public static int pow(int a,int b,int mod){
        int res=1;
        while (b>1){
            if (b%2==1){
                res=res*a%mod;
            }
            a=a*a%mod;b>>=1;
        }
        return res;
    }
    public static long  pow(long a,long b){
        long res=1;
        while (b>0){
            if (b%2==1){
                res*=a;
            }
            a*=a;b>>=1;
        }
        return res;
    }
    public static long pow(long a,long b,long mod){
        long res=1;
        while (b>1){
            if (b%2==1){
                res=res*a%mod;
            }
            a=a*a%mod;b>>=1;
        }
        return res;
    }
    public static int abs(int a){
        if (a<0){
            return -a;
        }
        return a;
    }
    public static long abs(long a){
        if (a<0){
            return -a;
        }
        return a;
    }
    public static int gcd(int x,int y){
        if (Math.min(x,y)==0){
            return Math.max(x,y);
        }
        int z;
        while (x%y>0){
            z=x%y;
            x=y;y=z;
        }
        return y;
    }
    public static long gcd(long x,long y){
        if (Math.min(x,y)==0){
            return Math.max(x,y);
        }
        long z;
        while (x%y>0){
            z=x%y;
            x=y;y=z;
        }
        return y;
    }
    public static void main(String[] args){
        Scanner sc=new Scanner(System.in);
        long a,b,n;
        a=sc.nextLong();b=sc.nextLong();n=sc.nextLong();
        if (n%3==2){
            print(a^b);
        } else if (n%3==0){
            print(a);
        } else {
            print(b);
        }
        sc.close();
    }
}