HDU 1394

#include<iostream>
#include<cstdio>
#include<cstring>
#define lson l, m, rt<<1
#define rson m+1, r, rt << 1|1
using namespace std;
const int maxn = 5000 + 31;
int Sum[maxn<<2];
int Num[maxn];

void PushUp(int rt)
{
    Sum[rt] = Sum[rt<<1] + Sum[rt<<1|1];
}

void Build(int l,int r,int rt)
{
    Sum[rt] = 0;
    if(l == r)
    {
        return ;
    }
    int m = (l + r) >> 1;
    Build(lson);
    Build(rson);
}

void UpDate(int l,int r,int rt,int val)
{
    if(l == val && r == val)
    {
        Sum[rt] = 1;
        return ;
    }
    int m = (l + r) >> 1;
    if(val > m) UpDate(rson,val);
    else UpDate(lson,val);
    PushUp(rt);
}

int GetNum(int L,int R,int l,int r,int rt)
{
    if(L <= l && r <= R)
    {
        return Sum[rt];
    }
    int ret = 0;
    int m = (l + r) >> 1;
    if(L <= m) ret += GetNum(L,R,lson);
    if(R > m)  ret += GetNum(L,R,rson);
    return ret;
}

int main()
{
    int n;
    while(scanf("%d",&n) != EOF)
    {
        Build(1,n,1);
        int sum = 0;
        int Min = 0;
        for(int i = 1; i <= n; ++i)
        {
            scanf("%d",&Num[i]);
            Num[i]++;
            sum += GetNum(Num[i],n,1,n,1);
            UpDate(1,n,1,Num[i]);
        }
        //cout << sum <<endl;
        Min = sum;
        for(int i = 1; i < n; ++i)
        {
            sum = sum + (n - 2*Num[i] + 1);
            Min = min(Min,sum);
        }
        printf("%d\n",Min);
    }
}