#include <bits/stdc++.h>
template <typename T>
void MACRO_VAR_Scan(T& t) {
  std::cin >> t;
}
template <typename First, typename... Rest>
void MACRO_VAR_Scan(First& first, Rest&... rest) {
  std::cin >> first;
  MACRO_VAR_Scan(rest...);
}
template <typename T>
void MACRO_VEC_ROW_Init(int n, T& t) {
  t.resize(n);
}
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Init(int n, First& first, Rest&... rest) {
  first.resize(n);
  MACRO_VEC_ROW_Init(n, rest...);
}
template <typename T>
void MACRO_VEC_ROW_Scan(int p, T& t) {
  std::cin >> t[p];
}
template <typename First, typename... Rest>
void MACRO_VEC_ROW_Scan(int p, First& first, Rest&... rest) {
  std::cin >> first[p];
  MACRO_VEC_ROW_Scan(p, rest...);
}
template <typename T>
void MACRO_OUT(const T t) {
  std::cout << t;
}
template <typename First, typename... Rest>
void MACRO_OUT(const First first, const Rest... rest) {
  std::cout << first << " ";
  MACRO_OUT(rest...);
}
template <class T>
inline T CHMAX(T& a, const T b) {
  return a = (a < b) ? b : a;
}
template <class T>
inline T CHMIN(T& a, const T b) {
  return a = (a > b) ? b : a;
}
template <class T>
using V = std::vector<T>;
template <class T>
using VV = V<V<T>>;
template <typename S, typename T>
std::ostream& operator<<(std::ostream& os, std::pair<S, T> p) {
  os << "(" << p.first << ", " << p.second << ")";
  return os;
}
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using PAIR = std::pair<ll, ll>;
using PAIRLL = std::pair<ll, ll>;
constexpr ll INFINT = (1 << 30) - 1;
constexpr ll INFINT_LIM = (1LL << 31) - 1;
constexpr ll INFLL = 1LL << 60;
constexpr ll INFLL_LIM = (1LL << 62) - 1 + (1LL << 62);
constexpr double EPS = 1e-10;
constexpr ll MOD = 998244353;
constexpr double PI = 3.141592653589793238462643383279;
template <class T, size_t N>
void FILL(T (&a)[N], const T& val) {
  for (auto& x : a) x = val;
}
template <class ARY, size_t N, size_t M, class T>
void FILL(ARY (&a)[N][M], const T& val) {
  for (auto& b : a) FILL(b, val);
}
template <class T>
void FILL(std::vector<T>& a, const T& val) {
  for (auto& x : a) x = val;
}
template <class ARY, class T>
void FILL(std::vector<std::vector<ARY>>& a, const T& val) {
  for (auto& b : a) FILL(b, val);
}
std::vector<std::pair<ll, ll>> primeFact(ll n) {
  std::vector<std::pair<ll, ll>> result;
  for (ll i = 2; i * i <= n; ++i) {
    ll divCount = 0;
    if (n % i == 0) {
      do {
        ++divCount;
        n /= i;
      } while (n % i == 0);
      result.emplace_back(i, divCount);
    }
  }
  if (n != 1) result.emplace_back(n, 1);
  return result;
}
signed main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  ;
  ll n;
  MACRO_VAR_Scan(n);
  ;
  std::vector<ll> a(n);
  for (auto& i : a) std::cin >> i;
  ;
  ll sum = 0;
  V<ll> b;
  for (ll i = 0; i < ll(n); ++i) sum += a[i];
  ll ans = INFLL;
  auto ev(primeFact(sum));
  for (const auto& p_ : ev) {
    ll k = p_.first;
    ll res = 0;
    VV<PAIR> vv;
    {
      V<PAIR> v;
      ll sum = 0;
      for (ll i = 0; i < ll(n); ++i) {
        ll t = a[i] % k;
        if (t == 0) continue;
        if (sum + t >= k) {
          if (sum + t == k) {
            v.emplace_back(i, t);
            vv.emplace_back(v);
            v.resize(0);
            sum = 0;
          } else {
            v.emplace_back(i, k - sum);
            vv.emplace_back(v);
            v.resize(0);
            v.emplace_back(i, t - (k - sum));
            sum = v[0].second;
          }
        } else {
          v.emplace_back(i, t);
          sum += t;
        }
      }
    }
    for (auto& v : vv) {
      ll sum = 0;
      ll me = -1;
      for (auto& p : v) {
        sum += p.second;
        if (sum * 2 >= k) {
          me = p.first;
          break;
        }
      }
      for (auto& p : v) res += std::abs(me - p.first) * p.second;
    }
    CHMIN(ans, res);
  }
  if (ans >= INFLL) ans = -1;
  MACRO_OUT(ans);
  std::cout << "\n";
  ;
  return 0;
}
