#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 = 1000010;
int mod = 1000000007;
const long long INF = 1e18;
int n, m, q;
int A[N], B[N], C[N];
char str[N];
int head[N], to[N * 2], nxt[N * 2], tot = 1;
void addEdge(int u, int v, int val) {
  tot++;
  nxt[tot] = head[u];
  to[tot] = v;
  head[u] = tot;
}
template <class T>
T mmax(T a, T b) {
  return a < b ? b : a;
}
template <class T>
T mmin(T a, T b) {
  return a < b ? a : b;
}
int countOne(long long set) {
  int res = 0;
  while (set) {
    res++;
    set &= set - 1;
  }
  return res;
}
bool contain(int set, int i) { return (set & (1 << i)) > 0; }
long long myPow(long long a, int 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;
}
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 * b % mod;
  if (res < 0) res += mod;
  return res;
}
template <class T>
void mySwap(T &a, T &b) {
  T tmp = a;
  a = b;
  b = tmp;
}
set<int> idx[N];
vector<int> nums[N];
int cnt[N];
bool check(int x, int y) {
  int cnt = 0;
  for (int i = 0; i < nums[x].size(); i++) {
    for (int j = 0; j < nums[y].size(); j++)
      if (nums[x][i] == nums[y][j]) cnt++;
  }
  return cnt == 2;
}
bool prime[N];
int main() {
  fast_io();
  cin >> n;
  long long sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> A[i];
    sum += A[i];
  }
  memset(prime, true, sizeof(prime));
  for (int i = 2; i * i < N; i++)
    if (prime[i]) {
      for (int j = i * i; j < N; j += i) {
        prime[j] = false;
      }
    }
  vector<int> candi;
  for (int i = 2; i <= 1000000; i++)
    if (prime[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;
}
