#include <stdio.h>

int main(){
	long long int x, y, z, n;
	scanf("%lld %lld %lld", &x, &y, &n);
	
	z = x^y;
	if(n%3 == 0){
		printf("%lld\n", x);
	}else if(n%3 == 1){
		printf("%lld\n", y);
	}else{
		printf("%lld\n", z);
	}
	
	
	return 0;
}