#pragma GCC optimize(3, "Ofast", "inline")

#include <bits/stdc++.h>

#define start ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define ll long long
#define LL long long
#define pii pair<int,int>
#define int ll
using namespace std;
const int maxn = (ll) 1e5 + 5;
const int mod = 1000000007;
const int inf = 0x3f3f3f3f3f3f3f3f;
int a[maxn];
int cnt = 0;
int sum[maxn];
int num[maxn];

signed main() {
    start;
    int n;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        int x;
        cin >> x;
        num[i] = num[i - 1] + x;//前缀数量
        if (x) {
            a[++cnt] = i;
            sum[i] = i;
        }
    }
    for (int i = 1; i <= n; ++i)//前缀坐标和
        sum[i] += sum[i - 1];
    int ans = inf;
    for (int i = 2; i <= cnt; ++i) {
        if (cnt % i == 0) {
            int tmp = 0;
            for (int k = i; k <= cnt; k += i) {//k为最后的糖果
                int first = a[k - i + 1];
                int last = a[k];
                int ave = a[k - i / 2];
                int num1 = num[ave] - num[first - 1];
                int num2 = num[last] - num[ave];
                int tot1 = sum[ave] - sum[first - 1];
                int tot2 = sum[last] - sum[ave];
                int t = num1 * ave - tot1 + tot2 - num2 * ave;
                tmp += t;
            }
            ans = min(ans, tmp);
        }
    }
    if (ans == inf)
        cout << -1;
    else
        cout << ans;
    return 0;
}