#include <set>

#include <map>

#include <cmath>

#include <queue>

#include <vector>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <iostream>

#include <algorithm>

using namespace std;

const int MAXN=;

int a[MAXN],n;

int lb(int i){return i&-i;}

void init(){memset(a,,sizeof(a));}

void add(int i,int v){for(;i<=n;a[i]+=v,i+=lb(i));}

int sum(int i){int ans=;for(;i;ans+=a[i],i-=lb(i));return ans;}

int query(int i,int j){return sum(j)-sum(i-);}

int num[MAXN],cnt,ans;

int main() {

    while(scanf("%d",&n)!=EOF){

        init(),cnt=;

        for(int i=;i<=n;i++)scanf("%d",&num[i]);

        for(int i=;i<=n;i++)cnt+=query(,n-num[i]-),add(n-num[i],);

        ans=cnt;

        for(int i=;i<n;i++)cnt+=(n--num[i])-num[i],ans=min(ans,cnt);

        cout<<ans<<endl;

    }

    return ;

}