Cake Cutting

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

void solve(){
    int m,n;
    cin>>m>>n;
    
    vector<array<int,2>>a(n);
    for(int i=0;i<n;i++) cin>>a[i][0], a[i][0]--;
    
    for(int i=0;i<n;i++) cin>>a[i][1], a[i][1]--;
    vector<int>cnt(m);
    int overlap=0;
    
    for(auto [s,e]:a){
        int ee= e;
        
        if(s>e)ee+=m;
        
        if(ee-s>=(m+1)/2) {
            overlap++;
            continue;
        }
        
        
        if(s<=e){
            cnt[s]++;
            cnt[e]--;
            
        }
        else{
            cnt[0]++;
            cnt[e]--;
            cnt[s]++;
        }
     }
    for(int i=1;i<m;i++){
        cnt[i]+= cnt[i-1];
    }
    int ans=0;
    
    for(int i=0;i<m;i++){
        ans= max( ans,cnt[i]+ cnt[( i+(m+1)/2)%m]);
        ans= max( ans, cnt[i]+ cnt[( i+m/2) %m ]);
        
    }
    cout<<ans+overlap << endl;
}
int main() {
	// your code goes here
	int t;
	cin>>t;
	
	while(t--){
	   solve();
	}

}