#include <bits/stdc++.h>
using namespace std;
long long read() {
  int f = 1;
  long long res = 0;
  char ch;
  do {
    ch = getchar();
    if (ch == '-') f = -f;
  } while (ch < '0' || ch > '9');
  do {
    res = res * 10 + ch - '0';
    ch = getchar();
  } while (ch >= '0' && ch <= '9');
  return f == 1 ? res : -res;
}
void fast_io() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
}
const int N = 1000005;
const int mod = 1e9 + 7;
const long long INF = 1e18;
int n, m;
long long A[N], B[N];
char str[N];
int head[N], to[N * 2], nxt[N * 2], tot = 1, weight[N * 2];
void addEdge(int u, int v, int w = 1) {
  tot++;
  nxt[tot] = head[u];
  to[tot] = v;
  head[u] = tot;
  weight[tot] = w;
}
void initGraph() {
  for (int i = 0; i <= n; i++) head[i] = 0;
  tot = 1;
}
int countOne(long long set) {
  int res = 0;
  while (set) {
    res++;
    set &= set - 1;
  }
  return res;
}
bool contain(long long set, int i) { return (set & (1LL << i)) > 0; }
long long myPow(long long a, long long p) {
  if (p == 0) return 1;
  long long res = myPow(a, p / 2);
  res *= res;
  res %= mod;
  if (p % 2 == 1) {
    res *= a;
    res %= mod;
  }
  return res % mod;
}
void addMode(long long &a, long long b) {
  a = (a + b) % mod;
  if (a < 0) a += mod;
}
long long mul(long long a, long long b) {
  long long res = a % mod * b % mod;
  if (res < 0) res += mod;
  return res;
}
int main() {
  fast_io();
  cin >> n;
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> A[i];
    sum += A[i];
  }
  vector<int> candi;
  for (int i = 2; i <= 1000000; i++) {
    if (sum % i == 0) candi.push_back(i);
  }
  if (candi.empty()) {
    cout << -1 << endl;
    return 0;
  }
  long long res = INF;
  for (int i = 0; i < candi.size(); i++) {
    int p = candi[i];
    long long tmp = 0;
    long long cur = 0;
    for (int j = 0; j < n; j++) {
      if (cur < (p + 1) / 2) {
        tmp += cur;
      } else {
        tmp += (p - cur);
      }
      cur = (cur + A[j]) % p;
    }
    res = min(res, tmp);
  }
  cout << res << endl;
  return 0;
}
