#include<bits/stdc++.h>
const int N=1e6+5;
int a[N],b[N],c[N];
long long ans=0;
using namespace std;
map<int, int> mp;
int main()
{
	int n;
	cin>>n;
	for(int i=1;i<=n;i++)
	{
		cin>>a[i];
	}
	for(int i=1;i<=n;i++)
	{
		cin>>b[i];
	}
	for(int i=1;i<=n;i++)
	{
		cin>>c[i];
	}
	for (int i = 1; i <= n; ++i)
	{
		mp[b[c[i]]]++; 
	}
	for (int i = 1; i <= n; ++i)
	{
		ans += mp[a[i]];
	}
	cout<<ans;
	return 0; 
}

#include

#define int long long

using namespace std;

const int N = 1e5 +10;

int a[N],b[N],c[N],n,m,sum;

signed main(){

cin>>n;

for(int i = 1;i<=n;i++){

cin>>m;

a[m]++;

}

for(int i = 1;i<=n;i++) cin>>b[i];

for(int i = 1;i<=n;i++){

cin>>m;

sum+=a[b[m]];

}

cout<<sum;

return 0;

}

赛时代码：

//t1 nest rp+=INF
#include<bits/stdc++.h>
using namespace std;

const int N=1e5+10;
int n,a[N],b[N],c[N],f[N];
long long ans;

int main()
{
//	freopen("nest.in","r",stdin);
//	freopen("nest.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
	{
		scanf("%d",&a[i]);
		f[a[i]]++;
	}
	for(int i=1;i<=n;++i)
	{
		scanf("%d",&b[i]);
	}
	for(int i=1;i<=n;++i)
	{
		scanf("%d",&c[i]);
		ans+=f[b[c[i]]];
	}
	printf("%lld",ans);
//	fclose(stdin);
//	fclose(stdout);
	return 0;
}