import sys
input=lambda:sys.stdin.readline().rstrip()
ans,F,pt=0,[0,0],0
*F,N=map(int,input().split())
while max(F):
	if (F[0]%2)|(F[1]%2)==1 and (F[0]%2)*2+F[1]%2-N%3-1!=0:
		ans+=1<<pt
	pt+=1
	F[0]>>=1
	F[1]>>=1
print(ans)