hdu 1394

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;

#define lson(i) l,mid,(i)*2
#define rson(i) mid+1,r,((i)*2+1)
#define ll rt*2
#define rr (rt*2+1)
const int MAXN = 5000+10;
struct Node{int l,r,tot;}nodes[MAXN*4];

int x[MAXN],n,d[MAXN],y[MAXN];

void Pushup(int rt)
{
    nodes[rt].tot = nodes[ll].tot + nodes[rr].tot;
}

void build(int rt, int l, int r)
{
    nodes[rt].l=l;
    nodes[rt].r=r;
    nodes[rt].tot=0;
    if(l == r)
    {
        return;
    }
    int mid=(l+r)/2;
    build(ll,l,mid);
    build(rr,mid+1,r);
}

void Update(int rt, int p, int v)
{
    if(nodes[rt].l == nodes[rt].r)
    {
        nodes[rt].tot=1;
        return;

    }
    int mid=(nodes[rt].l+nodes[rt].r)/2;
    if(p<=mid)
    {
        Update(rt*2,p,v);
    }
    else
    {
        Update(rr,p,v);
    }
    Pushup(rt);
}

int Query(int rt, int l, int r)
{
    if(l == nodes[rt].l && r == nodes[rt].r)
    {
        return nodes[rt].tot;
    }
    int mid=(nodes[rt].l+nodes[rt].r)>>1;
    if(r<=mid)return Query(ll,l,r);
    else
    {
        if(l>mid)
        {
            return Query(rr,l,r);
        }
        else
        {
            return Query(ll,l,mid)+Query(rr,mid+1,r);
        }
    }
}

int main()
{
    freopen("hdu1394.txt","r",stdin);
    while(~scanf("%d",&n))
    {
        for(int i=1;i<=n;i++)
        {
            scanf("%d",&x[i]);
            x[i]+=1;
        }
        build(1,1,n);
        for(int i=1;i<=n;i++)
        {
            Update(1,x[i],1);
            d[i]=Query(1,1,x[i])-1;
        }
        int sum=0,ans=n;
        for(int i=1;i<=n;i++)
        {
            y[i]=Query(1,1,x[i])-1-d[i];//y[i] x[i]右側比之小的数个数
            sum+=(i-1-d[i]);
        }
        /////////////////////////
       /* for(int i=1;i<=n;i++)
        {
            printf("i=%d d=%d y=%d\n",i,d[i],y[i]);
        }
        printf("sum=%d\n",sum);*/
        //////////////
        int c;
        ans=sum;
        for(int i=1;i<=n;i++)
        {
            c=y[i]+d[i];
            sum=sum-c+n-1-c;
            ans=min(ans,sum);
        }
        printf("%d\n",ans);
    }
    return 0;
}