#include <algorithm>
#include <cfloat>
#include <climits>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <functional>
#include <iostream>
#include <map>
#include <memory>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <utility>
#include <vector>
 
using namespace std;
 
#define sz size()
#define pb push_back
#define mp make_pair
#define fi first
#define se second
#define all(c) (c).begin(), (c).end()
#define rep(i,a,b) for(int i=(a);i<(b);++i)
#define clr(a, b) memset((a), (b) ,sizeof(a))
 
#define MOD 1000000009

int main(){
  int n;
  cin>>n;
  vector<int> v;
  rep(i,0,n){
    int a;
    cin>>a;
    v.pb(a);
  }
  rep(i,0,400){
    v.pb(0);
  }
  if(n==1&&v[0]==1){
    cout << 0 << endl;
    return 0;
  }
  int mn = 100000000;
  rep(i,1,150){
    int a1 = 0;
    int a2 = 0;
    int b = 1;
    int flag = 0;
    rep(j,0,350){
      if(v[j] > b){
        a1+=v[j]-b;
      }
      if(v[j] < b){
        a2+=b-v[j];
      }
      if(flag == 0){
        b++;
      }
      else{
        if(b >0){
          b--;
        }
      }
      if(b == i){
        flag = 1;
      }
    }
     if(a1 >= a2){
      mn = min(mn,a1);
    }
  }
  cout << mn << endl;
  return 0;
}