N = int(input())
A = list(map(int,input().split()))
A.sort()
S = 0
for i in range(min(24,N)):
  S += A[i]

for i in range(N - 1):
  if A[i + 1] == A[i]:
    S = min(S,A[i])
    break

dp = [0 for s in range(S + 1)]
dp[0] = 1
s = 0

inf = 1 << 61
ans = inf
for a in A:
  for ss in range(s,-1,-1):
    if dp[ss] == 0:
      continue
    if ss + a > S:
      continue
    if dp[ss + a]:
      ans = min(ans,ss + a)
    else:
      dp[ss + a] = 1
  s += a

S = sum(A)
R = S - 2 * ans
if R <= 0:
  R = -1
print(R)