#include <stdio.h>
#include <sys/time.h>

const int Mod = 30011;

struct timeval tt;
double tt_beg, tt_cur;

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()
{
	gettimeofday(&tt, NULL);
	tt_beg = tt.tv_sec + (double)tt.tv_usec / 1000000;
	
	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, min = sup, dp[3750001] = {1}, cur, prev;
	for (i = 0; i < N; i++) sum += A[i];
	for (i = 0, k = 0; i < N; i++) {
		for (j = k; j >= 0; j--) dp[j+A[i]] += dp[j];
		
		k += A[i];
		chmin(&k, sum / 2);
		for (j = 0; j <= k; j++) {
			dp[j] %= Mod;
			if (dp[j] > 1) chmin(&min, j);
		}
		
		gettimeofday(&tt, NULL);
		tt_cur = tt.tv_sec + (double)tt.tv_usec / 1000000;
		if (tt_cur - tt_beg > 1.95 || (i > 0 && A[i] == A[i-1])) break;
	}
	if (min < sup && sum - min * 2 > 0) printf("%d\n", sum - min * 2);
	else printf("-1\n");
	fflush(stdout);
	return 0;
}