import sys

def input(): return sys.stdin.readline().strip()
def list2d(a, b, c): return [[c] * b for i in range(a)]
def list3d(a, b, c, d): return [[[d] * c for k in range(b)] for i in range(a)]
def list4d(a, b, c, d, e): return [[[[e] * d for k in range(c)] for k in range(b)] for i in range(a)]
def ceil(x, y=1): return int(-(-x // y))
def INT(): return int(input())
def MAP(): return map(int, input().split())
def LIST(N=None): return list(MAP()) if N is None else [INT() for i in range(N)]
def Yes(): print('Yes')
def No(): print('No')
def YES(): print('YES')
def NO(): print('NO')
sys.setrecursionlimit(10**9)
INF = 10**19
MOD = 10**9 + 7
EPS = 10**-10

N = INT()
A = LIST()
B = LIST()

AB = [0] * N
for i in range(N):
    AB[i] = A[i] - B[i]

ans = 0
if N == 2:
    if AB[0] < AB[1]:
        AB[0], AB[1] = AB[1], AB[0]
    ans += -AB[1]
    AB[0] += AB[1]
    AB[1] = 0
    if sum(AB) == 0:
        print(ans)
    else:
        print(-1)
    exit()

cnt = 0
idx = -1
for i in range(N):
    if AB[i] < 0:
        cnt += 1
        idx = i
if cnt >= 2:
    print(-1)
    exit()

while cnt:
    cnt = 0
    nxt = -1
    ans += -AB[idx]
    for i in range(N):
        if i != idx:
            AB[i] += AB[idx]
            if AB[i] < 0:
                nxt = i
                cnt += 1
    if cnt >= 2:
        print(-1)
        exit()
    AB[idx] = 0
    idx = nxt

ok = 1
se = set()
for i in range(N):
    se.add(AB[i]%2)
if len(se) != 1:
    print(-1)
    exit()

if sum(AB) % (N-2) == 0:
    ans += sum(AB) // (N-2)
    print(ans)
else:
    print(-1)