#include <string>
#include <iostream>
#include <algorithm>
#include <queue>
#include <stack>
#include <vector>
#include <deque>
#include <functional>
#include <climits>
#include <set>
#include <map>
#include <cassert>
#include <cmath>
using namespace std;
using ll = long long;
ll n;
ll ar[100005];
ll f(ll d)
{
ll ans = 0;
for (ll i = 0; i < n; i++)
ans += abs(d * i - ar[i]);
return ans;
}
signed main()
{
cin.tie(NULL); cout.tie(NULL);
ios_base::sync_with_stdio(false);
cin >> n;
for (int i = 0; i < n; i++) cin >> ar[i];
ll l = 0, r = ar[n - 1];
while (r - l >= 3)
{
ll p = (l * 2 + r) / 3, q = (l + r * 2) / 3;
if (f(p) <= f(q)) r = q;
else l = p;
}
ll ans = 1e15;
for (int i = l; i <= r; i++) ans = min(ans, f(i));
cout << ans;
}
