1776H - Beppa and SwerChat - CodeForces Solution

#include <bits/stdc++.h>
using namespace std;
using ll=long long;


int main() {
	// your code goes here
	int t;cin>>t;
	
	while(t--){
	    int n;cin>>n;
	   
	    int a[n];
	    int b[n];
	    int m[n+1];
	    for(int i=0;i<n;i++){
	        cin>>a[i];
	        m[a[i]]=i;
	    }int k=0;
	    for(int i=0;i<n;i++){
	        cin>>b[i];
	        
	        
	    }
	    for(int i=n-1;i>0;i--){
	        if(m[b[i]]<m[b[i-1]]){
	            k=i;
	            break;
	        }
	    }
	    cout<<k<<endl;
	    
	   
	    
	    
	}
	return 0;
}