N = int(input())
A = list(map(int, input().split()))
B = list(map(int, input().split()))
if N==2 and B[0]-A[0] == -(B[1]-A[1]):
    print(abs(B[0]-A[0]))
elif N == 2:
    print(-1)
    exit()
s = 0
m = []
for i in range(N):
    s += (B[i]-A[i])
    m.append(B[i]-A[i])
sm, mod = divmod(s, 2-N)
if mod != 0:
    print(-1)
    exit()
else:
    res = 0
    for i in range(N):
        if (m[i]+sm)%2 == 1:
            print(-1)
            exit()
        else:
            res += abs((m[i]+sm)//2)
    print(res)