#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#include <map>

using namespace std;

int main(){
    int num[101],jou[101],n,ans=0,sum=0,retu,sute=0;
    
    scanf("%d",&n);
    
    for(int i=1;i<=n;i++){
        scanf("%d",&num[i]);
        sum+=num[i];
    }
    
    for(int i=1;i<=100;i++)
        jou[i]=i*i;
    
    for(retu=1;;retu++){
        if(jou[retu]>sum)
            break;
    }
    
    retu=(retu-1)*2-1;
    
    for(int i=1;i<=retu;i++){
        if(i<=retu/2+(retu%2))
            ans+=num[i]-i;
        else
            ans+=num[i]-(retu-i+1);
    }
    
    
    for(int i=retu+1;i<=n;i++){
        sute+=num[i];
    }

    if(sute==-1*ans){
        ans=sute;
    }else if(sute>-1*ans && ans<0){
        ans=abs(ans)+sute+ans;
    }else{
        ans=abs(ans)+sute;
    }
    
    printf("%d\n",abs(ans));
    
    return 0;
}