1
int n;
2
ll cnt;
3
vector<ll> arr,tree;
4

5
void add(ll i,ll x,ll len){
6
  while(i<=len){
7
    tree[i]+=x;
8
    i+=lowbit(i);
9
  }
10
}
11

12
ll sum(ll i){
13
  ll ans=0;
14
  while(i>0){
15
    ans+=tree[i];
16
    i-=lowbit(i);
17
  }
18
  return ans;
19
}
20

21
void solve() {
22
  cin>>n;
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  arr.resize(n);
24
  vector<int> ls;
25
  for(int i=0;i<n;i++){
26
    cin>>arr[i];
27
    ls.push_back(arr[i]);
28
  }
29
  sort(ls.begin(),ls.end());
30
  ls.erase(unique(ls.begin(),ls.end()),ls.end());
31
  int m=ls.size();
32
  tree.assign(m+1,0LL);
33
  for(int i=n-1;i>=0;i--){
34
    int it=lower_bound(ls.begin(),ls.end(),arr[i])-ls.begin()+1;
35
    cnt+=sum(it-1);
36
    add(it,1,m);
37
  }
38
  cout<<cnt;
39
}

1
int n;
2
ll cnt;
3
vector<ll> arr,b;
4
ll tree[N],pos[N];
5

6

7
void add(ll i,ll x){
8
  while(i<=n){
9
    tree[i]+=x;
10
    i+=lowbit(i);
11
  }
12
}
13

14
ll sum(ll i){
15
  ll ans=0;
16
  while(i>0){
17
    ans+=tree[i];
18
    i-=lowbit(i);
19
  }
20
  return ans;
21
}
22

23
void solve() {
24
  cin>>n;
25
  arr.assign(n+1,0);
26
  b.assign(n+1,0);
27
  for(int i=1;i<=n;i++){
28
    cin>>arr[i];
29
    pos[arr[i]]=i;
30
  }
31
  for(int i=1;i<=n;i++){
32
    cin>>b[i];
33
  }
34
  for(int i=n;i>=1;i--){
35
    int curp=pos[b[i]];
36
    cnt+=sum(curp-1);
37
    add(curp,1);
38
  }
39
  cout<<cnt;
40
}