#include <iostream>
#include <algorithm>
using namespace std;

inline long long read() {
    long long num = 0, fg = 1;
    char c = getchar();
    while(!isdigit(c)) {
        if (c == '-') fg = -fg;
        c = getchar();
    }
    while(isdigit(c)) {
        num = num * 10 + c - '0';
        c = getchar();
    }
    return num * fg;
}

int solve(int);
int main() {
    freopen("edit.in", "r", stdin);
    freopen("edit.out", "w", stdout);
    int T = read();
    for (int i = 1; i <= T; i++) solve(i);
    //solve();
    return 0;
}

#define MAXN 300005
char s[3][MAXN];
char t[3][MAXN];
int n;

struct Line {
    int l, r;
    int tim[2];
    void clear() {
        this->l = this->r = 0;
        for (int i = 0; i <= 1; i++) this->tim[i] = 0;
    }
    void debug() {
        printf("(%d, %d) = %d, %d\n", l, r, tim[0], tim[1]);
    }
    bool operator<(const Line& li) const {
        return this->l < li.l;
    }
};
Line a[3][MAXN];
int tot[3];

int solve(int id) {
    // clear...
    for (int st = 1; st <= 2; st++)
        for (int i = 0; i < MAXN; i++) a[st][i].clear();
    for (int i = 1; i <= 2; i++) tot[i] = 0;

    // init...
    n = read();
    //printf("n = %d\n", n);
    for (int i = 1; i <= 2; i++) scanf("%s", &s[i][1]);
    for (int i = 1; i <= 2; i++) scanf("%s", &t[i][1]);


    for (int st = 1; st <= 2; st++) {
        for (int i = 1; i <= n; i++) {
            if (t[st][i] == '1') {
                if (i == 1 || t[st][i - 1] == '0') tot[st]++;
                if (!a[st][tot[st]].l) a[st][tot[st]].l = i;
                a[st][tot[st]].r = i;
                a[st][tot[st]].tim[s[st][i] - '0']++;
                //printf("st = %d, i = %d, tot = %d\n", st, i, tot[st]);
            }
        }
        for (int i = 1; i <= n; i++) {
            if (t[st][i] == '0') {
                tot[st]++;
                a[st][tot[st]].l = a[st][tot[st]].r = i;
                a[st][tot[st]].tim[s[st][i] - '0']++;
            }
        }
    }
    for (int i = 1; i <= 2; i++) sort(a[i] + 1, a[i] + tot[i] + 1);
    /*
    if (id == 7)
    for (int st = 1; st <= 2; st++) {
        for (int i = 1; i <= tot[st]; i++) a[st][i].debug();
        printf("\n");
    }
    //*/
    int ans = 0;

    int pt = 1;
    for (int i = 1; i <= tot[1]; i++) {
        int nr = a[1][i].r;
        //printf("pt1 = %d, pt2 = %d, ans = %d\n", i, pt, ans);
        //if(id == 7) a[1][i].debug(), a[2][pt].debug();
        //printf("\n");
        while(pt <= tot[2] && a[2][pt].r <= nr) {
            int lent = a[2][pt].r - a[2][pt].l + 1;
            for (int j = 0; j < 2; j++) {
                int delta = min(min(a[1][i].tim[j], a[2][pt].tim[j]), lent);
                ans += delta;
                a[1][i].tim[j] -= delta;
                a[2][pt].tim[j] -= delta;
                //if (id == 7) printf("r %d delta = %d\n", nr, delta);
            }
            //if (id == 7) printf("\n");
            pt++;
        }
        //printf("r = %d, pt = %d, ans = %d\n", nr, pt, ans);
        if (pt <= tot[2] && a[2][pt].l <= nr) {
            int lent = nr - a[2][pt].l + 1;
            for (int j = 0; j < 2; j++) {
                int delta = min(min(a[1][i].tim[j], a[2][pt].tim[j]), lent);
                ans += delta;
                a[1][i].tim[j] -= delta;
                a[2][pt].tim[j] -= delta;
                lent -= delta;
                //if (id == 7) printf("r %d delta = %d\n", nr, delta);
            }

            //if (id == 7) printf("\n");
            a[2][pt].l = nr + 1;
            if (a[2][pt].l > a[2][pt].r) pt++;
            //printf("nr = %d, [%d].l = %d ans = %d\n", nr, pt, a[2][pt].l, ans);
        }
        //printf("r = %d, i = %d, ans = %d\n", nr, i, ans);
    }

    printf("%d\n", ans);
    return 0;
}
/*
10
10
0110111100
1111111100

1110000100
0110111011
ans = 8;

9
101111111
100111000

110111011
011111111
ans = 5;

1
3
1010
1100
1110
1110
10
0110111100
1111111110
1110111111
1111110111
*/