#include <stdio.h>

void chmin(int *a, int b)
{
	if (*a > b) *a = b;
}

void merge_sort(int n, int x[])
{
	static int y[3001] = {};
	if (n <= 1) return;
	merge_sort(n / 2, &(x[0]));
	merge_sort((n + 1) / 2, &(x[n/2]));
	
	int i, p, q;
	for (i = 0, p = 0, q = n / 2; i < n; i++) {
		if (p >= n / 2) y[i] = x[q++];
		else if (q >= n) y[i] = x[p++];
		else y[i] = (x[p] < x[q])? x[p++]: x[q++];
	}
	for (i = 0; i < n; i++) x[i] = y[i];
}

int main()
{
	int i, N, A[3001];
	scanf("%d", &N);
	for (i = 0; i < N; i++) scanf("%d", &(A[i]));
	merge_sort(N, A);
	
	const int sup = 1 << 25;
	int j, k, sum = 0, dp[2][7500001], cur, prev;
	for (j = 1, dp[0][0] = 0, dp[1][0] = 0; j <= 7500000; j++) {
		dp[0][j] = sup;
		dp[1][j] = sup;
	}
	for (i = 0; i < N; i++) sum += A[i];
	for (i = 0, k = 0, cur = 1, prev = 0; i < N; i++, cur ^= 1, prev ^= 1) {
		for (j = 0; j <= k; j++) dp[cur][j] = dp[prev][j];
		for (j = 0; j <= k; j++) {
			if (dp[prev][j] == sup) continue;
			chmin(&(dp[cur][j+A[i]]), dp[prev][j] + A[i]);
			if (j > A[i]) chmin(&(dp[cur][j-A[i]]), dp[prev][j]);
			else if (j < A[i]) chmin(&(dp[cur][A[i]-j]), dp[prev][j] + A[i] - j);
			else {
				if (dp[cur][0] == 0) dp[cur][0] = dp[prev][j];
				else chmin(&(dp[cur][0]), dp[prev][j]);
			}
		}
		k += A[i];
		chmin(&k, sum / 2);
		
		if (dp[cur][0] != 0 || (i > 0 && A[i] == A[i-1])) {
			cur ^= 1;
			prev ^= 1;
			break;
		}
	}
	if (dp[prev][0] != 0) printf("%d\n", sum - dp[prev][0] * 2);
	else printf("-1\n");
	fflush(stdout);
	return 0;
}