#include <bits/stdc++.h>
using namespace std;
template <typename S, typename T>
ostream& operator<<(ostream& out, pair<S, T> const& p) {
  out << '(' << p.first << ", " << p.second << ')';
  return out;
}
template <typename T>
ostream& operator<<(ostream& out, vector<T> const& v) {
  long long l = v.size();
  for (long long i = 0; i < l - 1; i++) out << v[i] << ' ';
  if (l > 0) out << v[l - 1];
  return out;
}
template <typename T>
void trace(const char* name, T&& arg1) {
  cout << name << " : " << arg1 << '\n';
}
template <typename T, typename... Args>
void trace(const char* names, T&& arg1, Args&&... args) {
  const char* comma = strchr(names + 1, ',');
  cout.write(names, comma - names) << " : " << arg1 << " | ";
  trace(comma + 1, args...);
}
const long long MOD = 1e9 + 7;
const long long INF = 1e18;
const double EPS = 1e-9;
const long long N = 500005;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
long long rand(long long l, long long r) {
  uniform_int_distribution<long long> uid(l, r);
  return uid(rng);
}
long long a[1000001];
long long s[1000001];
long long n;
long long cost(long long k) {
  long long ret = 0;
  for (long long i = 0; i < n; i++) {
    ret += min(s[i] % k, k - (s[i] % k));
  }
  return ret;
}
void solve(long long x) {
  cin >> n;
  for (long long i = 0; i < n; i++) {
    cin >> a[i];
  }
  s[0] = a[0];
  for (long long i = 1; i < n; i++) {
    s[i] = s[i - 1] + a[i];
  }
  long long ans = 1e18;
  long long num = s[n - 1], p = 2;
  while (p * p <= num) {
    if (num % p == 0) {
      ans = min(ans, cost(p));
      while (num % p == 0) {
        num /= p;
      }
    }
    p++;
  }
  if (num > 1) {
    ans = min(ans, cost(num));
  }
  cout << (ans == 1e18 ? -1 : ans) << '\n';
}
int32_t main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cout.precision(12);
  long long t;
  t = 1;
  long long i = 0;
  while (i < t) {
    solve(i + 1);
    i++;
  }
}
