T = int(input())
for i in range(T):
    L, R = map(int, input().split())
    if R == L:
        print(2*L)
    elif L%2 == R%2:
        a = (R-L+2)//2
        if a%2 == 0:
            print((a%4)//2)
        else:
            print((R+L)^((a%4)//2))
    else:
        a = (R-L+1)//2
        if a%2 == 0:
            print((a%4)//2)
        else:
            print(((a%4)//2)^(L+R)^(L+R-1))