//include
//------------------------------------------
#include <vector>
#include <list>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <bitset>
#include <algorithm>
#include <functional>
#include <numeric>
#include <utility>
#include <sstream>
#include <iostream>
#include <iomanip>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <string>
#include <cstring>
#include <ctime>
#include <fstream>
using namespace std;

//conversion
//------------------------------------------
inline int toInt(string s) {int v; istringstream sin(s);sin>>v;return v;}
template<class T> inline string toString(T x) {ostringstream sout;sout<<x;return sout.str();}

//math
//-------------------------------------------
template<class T> inline T sqr(T x) {return x*x;}

//typedef
//------------------------------------------
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<string> VS;
typedef pair<int, int> PII;
typedef pair<long, long> PLL;
typedef long long LL;
//container util
//------------------------------------------
#define ALL(a)  (a).begin(),(a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define PB push_back
#define MP make_pair
#define SZ(a) int((a).size())
#define EACH(i,c) for(typeof((c).begin()) i=(c).begin(); i!=(c).end(); ++i)
#define EXIST(s,e) ((s).find(e)!=(s).end())
#define SORT(c) sort((c).begin(),(c).end())

//repetition
//------------------------------------------
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n)  FOR(i,0,n)

//constant
//--------------------------------------------
const double EPS = 1e-10;
const double PI  = acos(-1.0);

//clear memory
#define CLR(a) memset((a), 0 ,sizeof(a))
#define INF 100000

int A[1002],B[1002];
int main(){
	int N;
	cin>>N;
	int sum=0;
	CLR(A);
	REP(i,N){
		cin>>A[i];
		sum+=A[i];
	}
	int res=INF;
	int cnt=1;
	for(int i=1;;i+=2){
		if(cnt*cnt>sum)break;
		int N2=i;
		int temp=0;
		CLR(B);
		B[0]=1;
		int pos;
		for(pos=1;pos<(N2+1)/2;pos++)B[pos]=B[pos-1]+1;
		for(;pos<N2;pos++)B[pos]=B[pos-1]-1;
		REP(i,N2)if(A[i]-B[i]>0)temp+=A[i]-B[i];
		/*REP(i,N2)cout<<A[i]<<" ";
		cout<<endl;
		REP(i,N2)cout<<B[i]<<" ";
		cout<<endl;*/
		res=min(res,temp);
		cnt++;
	}
	cout<<res<<endl;
	return 0;
}