#include <bits/stdc++.h>
using namespace std;
const int N=1e5+10;
int t,n,g1[N][2],g2[N][2],gg1[N][2],gg2[N][2],nxt1[N],nxt2[N];
char s1[N],s2[N],ss1[N],ss2[N];
int main()
{
	freopen("edit.in","r",stdin);
	freopen("edit.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);cout.tie(0);
	cin>>t;//清空 
	while(t--)
	{
		cin>>n; 
		cin>>ss1>>ss2;
		for(int i=1;i<=n;i++)
		{
			g1[i][1]=g1[i-1][1]+(ss1[i-1]=='1');//一的个数
			g2[i][1]=g2[i-1][1]+(ss2[i-1]=='1'); 
			g1[i][0]=g1[i-1][0]+(ss1[i-1]=='0');//零的个数
			g2[i][0]=g2[i-1][0]+(ss2[i-1]=='0'); 
		} 
		cin>>s1>>s2;
		int las1=0,las2=0;
		for(int i=1;i<=n;i++)
		{
			if(s1[i-1]=='0')
			{
				gg1[i][1]=g1[i-1][1]-g1[las1][1];
				gg1[i][0]=g1[i-1][0]-g1[las1][0]; 
				nxt1[las1]=i;
				las1=i;
			}
			if(s2[i-1]=='0')
			{
				gg2[i][1]=g2[i-1][1]-g2[las2][1];
				gg2[i][0]=g2[i-1][0]-g2[las2][0]; 
				nxt2[las2]=i;
				las2=i;
			}
		} 
		gg1[n+1][1]=g1[n][1]-g1[las1][1];gg1[n+1][0]=g1[n][0]-g1[las1][0]; 
		gg2[n+1][1]=g2[n][1]-g2[las2][1];gg2[n+1][0]=g2[n][0]-g2[las2][0]; 
		nxt1[las1]=nxt2[las2]=n+1;
		int zhi1=nxt1[0],zhi2=nxt2[0],ans=0,jc=n;
		while(zhi1!=n+1||zhi2!=n+1)
		{
			int ys=0,ls=0;
			if(zhi1==zhi2)
			{
				ys=min(gg1[zhi1][1],gg2[zhi2][1]),ls=min(gg1[zhi1][0],gg2[zhi2][0]);
				ans+=ys+ls+(ss1[zhi1-1]==ss2[zhi2-1]);
 				zhi1=nxt1[zhi1],zhi2=nxt2[zhi2];
 				jc=n;
 			}
 			else if(zhi1>zhi2)
 			{
 				if(ss2[zhi2-1]=='1')ys=min(gg1[zhi1][1],1),gg1[zhi1][1]-=ys;
			 	else ls=min(gg1[zhi1][0],1),gg1[zhi1][0]-=ls;
			 	ans+=ys+ls;
 				ys=min(gg1[zhi1][1],gg2[zhi2][1]),ls=min(gg1[zhi1][0],gg2[zhi2][0]);
 				if(ys+ls>jc)ys=min(ys,jc),ls=min(ls,jc-ys); 
 				ans+=ys+ls;gg1[zhi1][1]-=ys;gg1[zhi1][0]-=ls;
 				jc=zhi1-zhi2-1;
				zhi2=nxt2[zhi2];
			}
			else 
 			{
			 	if(ss1[zhi1-1]=='1')ys=min(gg2[zhi2][1],1),gg2[zhi2][1]-=ys;
			 	else ls=min(gg2[zhi2][0],1),gg2[zhi2][0]-=ls;
			 	ans+=ys+ls;
				ys=min(gg1[zhi1][1],gg2[zhi2][1]),ls=min(gg1[zhi1][0],gg2[zhi2][0]);
				if(ys+ls>jc)ys=min(ys,jc),ls=min(ls,jc-ys); 		
 				ans+=ys+ls;gg2[zhi2][1]-=ys;gg2[zhi2][0]-=ls;
 				jc=zhi2-zhi1-1; 
 				zhi1=nxt1[zhi1];
			}
		}
		ans+=min(gg1[zhi1][1],gg2[zhi2][1])+min(gg1[zhi1][0],gg2[zhi2][0]);
		cout<<ans<<'\n'; 
	} 
	return 0;
 }