#include <iostream>
#include <vector>
#include <algorithm>
#include <climits>
using namespace std;

vector<vector<int>> vv;

void calc(int n){
  if(n%2==0) n-=1;
  for(int i=1;i<=n;i+=2){
    vector<int> v;
    if(i==1){
      v.push_back(1);
    } else if(i==3){
      v.push_back(1);
      v.push_back(2);
      v.push_back(1);
    } else {
      for(int j=1;j<=i/2;++j){
        v.push_back(j);
      }
      v.push_back(i/2+1);
      for(int j=i/2;j>=1;--j){
        v.push_back(j);
      }
    }
    vv.push_back(v);
  }
}

int main(){
  int N; cin>>N;
  vector<int> v(N);
  int sum_block=0;
  for(int i=0;i<N;++i){
    cin>>v[i];
    sum_block+=v[i];
  }
  calc(N);
  int cnt=INT_MAX;
  for(int i=0;i<vv.size();++i){
    int column=vv[i].size();
    for(int j=0;j<v.size()-column+1;++j){
      for(int k=j;k<j+column;++k){
        int sum_block2=0;
        int stock_block=0;
        int supply_block=0;
        int move_block=0;
        for(int l=j;l<=k;++l){
          sum_block2+=v[l];
          int diff_block=v[l]-vv[i][l-j];
          if(diff_block>=0) stock_block+=diff_block,move_block+=diff_block;
          else if(diff_block<0 && stock_block>=diff_block*-1) stock_block-=diff_block;
          else if(diff_block<0 && stock_block<diff_block*-1) supply_block+=(diff_block*-1-stock_block),move_block+=(diff_block*-1-stock_block),stock_block=0;
        }
        if(supply_block>(sum_block-sum_block2)) move_block=INT_MAX;
        else move_block+=(sum_block-sum_block2-supply_block);
        if(move_block<cnt) cnt=move_block;
      }
    }
  }
  cout<<cnt<<endl;
  return 0;
}