#include<stdio.h>
int main()
{
    int t,j;
    freopen("hamming.in","r",stdin);
    scanf("%d",&t);
    for(j=0;j<t;j++){
        int i,n,mn,cnt=0,acnt=0,ocnt=0;
        scanf("%d",&n);
        char s[2019],e[2019];
        scanf("%s",s);
        scanf("%s",e);
        for(i=0;i<n;i++){
            if(s[i]==e[i]){
                if(s[i]=='0')
                    ocnt++;
                else if(s[i]=='1')
                    acnt++;
                continue;
            }
            cnt++;
        }
        mn=ocnt;
        if(acnt<ocnt)
            mn=acnt;
        cnt=cnt+mn+mn;
        printf("%d\n",cnt);
    }
    return 0;
}