#include<bits/stdc++.h>
using namespace std;
#define ll long long
ll a[100005];
//ll b[100005];
ll n;
ll res=5000;
ll maxx=0;
void sinh(ll i, ll sum){
if (sum>=res) return;
if (i>n){
for (int j=2;j<n;j++){
ll x=j+1;
while (x<=n && a[j]==a[x]){
x++;
}
if (x>n){
j=x;
continue;
}
if (a[j-1]>a[j] && a[j]>a[x]) return;
if (a[j-1]<a[j] && a[j]<a[x]) return;
// if (a[j-1]>a[j] && a[j]>a[x])
}
res=min(res,sum);
}
for (int xx=-1000;xx<=1000;xx++){
if (a[i]+xx<0) continue;
if (a[i]+xx>maxx) continue;
a[i]+=xx;
sinh(i+1,sum+abs(xx));
a[i]-=xx;
}
}
int main(){
// ll n;
cin>>n;
for (int i=1;i<=n;i++){ cin>>a[i]; maxx=max(maxx,a[i]);}
sinh(1,0);
cout<<res;
}
