WA on #19

#include<iostream>
#include<cstring>
using namespace std;
int a[100005],b[100005];
int a0[100005],b0[100005],a1[100005],b1[100005];
int ra[100005],rb[100005];

int main(){
    ios::sync_with_stdio(0);
    //freopen("edit.in","r",stdin);
    //freopen("edit.out","w",stdout);
    int t;
    cin>>t;
    while(t--){
        int n;
        string s1,s2,t1,t2;
        cin>>n>>s1>>s2>>t1>>t2;
        int cnt1=1,cnt2=1;
        for(int i=0;i<n;i++){
            if(t1[i]=='0'){
               cnt1++;
               a[i]=cnt1;
               if(i!=n-1) cnt1++;
            }
            else a[i]=cnt1;
            if(t2[i]=='0'){
                cnt2++;
                b[i]=cnt2;
                cnt2++;
            }
            else b[i]=cnt2;
        }
        for(int i=0;i<n;i++){
            if(s1[i]=='0') a0[a[i]]++;
            if(s1[i]=='1') a1[a[i]]++;
            if(s2[i]=='0') b0[b[i]]++;
            if(s2[i]=='1') b1[b[i]]++;
        }
        int ans=0;
        for(int i=0;i<n;i++){
            if(a0[a[i]]>0 && b0[b[i]]>0){
                ans++;
                a0[a[i]]--;
                b0[b[i]]--;
            }
            else if(a1[a[i]]>0 && b1[b[i]]>0){
                ans++;
                a1[a[i]]--;
                b1[b[i]]--;
            }
        }
        cout<<ans<<'\n';
        memset(a0,0,sizeof(a0));
        memset(a1,0,sizeof(a1));
        memset(b0,0,sizeof(b0));
        memset(b1,0,sizeof(b1));
    }
    return 0;
}