N = int(input())
A = list(map(int, input().split()))

INF = 1<<60

MAX = 5000
if N <= 20:
    MAX *= N
elif N <= 200:
    MAX *= 10
else:
    MAX *= 2
dp = [[INF]*(MAX*2+1) for _ in range(N+1)]
dp[0][MAX] = 0
ans = INF
for i in range(N):
    for j in range(MAX*2+1):
        if dp[i][j] == INF: continue
        dp[i+1][j] = min(dp[i+1][j], dp[i][j])
        if j+A[i] <= MAX*2:
            if j+A[i] == MAX:
                ans = min(ans, dp[i][j]+A[i])
            dp[i+1][j+A[i]] = min(dp[i+1][j+A[i]], dp[i][j]+A[i])
        if A[i] <= j:
            if j-A[i] == MAX:
                ans = min(ans, dp[i][j])
            dp[i+1][j-A[i]] = min(dp[i+1][j-A[i]], dp[i][j])

if ans < (sum(A)+1)//2:
    print(sum(A)-ans*2)
else:
    print(-1)