#include<queue>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
#define N 202300
#include "shoes.h"
using namespace std;
ll n,x,y,ans,c[N],p[N];
queue<ll>d[N];
void add(ll x,ll y)
{
x++;
for(;x<=n*2;x+=x&-x)
c[x]+=y;
return;
}
ll ask(ll x)
{
x++;
ll sum=0;
for(;x;x-=x&-x)
sum+=c[x];
return sum;
}
long long count_swaps(std::vector<int> s) {
n=s.size()/2;
ans=0;
for(ll i=2*n-1;i>=0;--i){
add(i,1);
x=s[i];
d[x+n].push(i);
}
for(ll i=2*n-1;i>=0;--i){
if(p[i])continue;
x=s[i];
y=-s[i];
if(x<0)ans++;
ll j=d[y+n].front();
d[x+n].pop();
d[y+n].pop();
ans+=ask(i-1)-ask(j);
add(i,-1);
add(j,-1);
p[i]=1;
p[j]=1;
}
return ans;
}
//int main()
//{
// vector<int>aaa;
// aaa.push_back(2);
// aaa.push_back(1);
// aaa.push_back(-1);
// aaa.push_back(-2);
// printf("%lld\n",count_swaps(aaa));
// return 0;
//}
