/* Problem URL: https://codeforces.com/problemset/problem/2022/C */

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template <class T, class comp = less<>>
using ordered_set = tree<T, null_type , comp , rb_tree_tag , tree_order_statistics_node_update>;

#define V vector

#define rmin(a, b) a = min(a, b)
#define rmax(a, b) a = max(a, b)

#define rep(i, lim) for (int i = 0; i < (lim); i++)
#define nrep(i, s, lim) for (int i = s; i < (lim); i++)

#define repv(i, v) for (auto &i : (v))
#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
#define sortv(v) sort(v.begin(), v.end())
#define all(v) (v).begin(), (v).end()

using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vvvvi = vector<vvvi>;

using ll = long long;

using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;

template<class v>
auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
    os << vec[0];
    for (size_t i = 1; i < vec.size(); i++) {
        os << ' ' << vec[i];
    }
    os << '\n';
    return os;
}

template<class v>
auto operator>>(istream &is, vector<v> &vec)->istream& {
    for (auto &i : vec) {
        is >> i;
    }
    return is;
}

template<class v>
auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
    for (auto &i : vec) {
        os << i[0];
        for (size_t j = 1; j < i.size(); j++) {
            os << ' ' << i[j];
        }
        os << '\n';
    }
    return os;
}

template<class v>
auto operator>>(istream  &is, vector<vector<v>> &vec)->istream& {
    for (auto &i : vec) {
        for (auto &j : i) {
            is >> j;
        }
    }
    return is;
}

const int oo = INT32_MAX >> 1;
const ll OO = INT64_MAX >> 1;


void pre()
{

}

#define TEST 1

void solve()
{
    int n;
    cin >> n;
    string a, b;
    cin >> a >> b;

    vvi act(2, vi(n));
    rep(i, n) {
        act[0][i] += a[i] == 'A';
        act[1][i] += b[i] == 'A';
    }

    vvi memo(n, vi(3, -1));

    function<int(int, int)> dp = [&](int i, int s) {
        if (i >= n - 1) {
            if (s == 1) {
                return (act[0][n - 1] + act[0][n - 2] + act[1][n - 1] + 1) / 3;
            }

            if (s == 2) {
                return (act[0][n - 1] + act[1][n - 1] + act[1][n - 2] + 1) / 3;
            }

            return 0;
        }

        int &ans = memo[i][s];
        if (ans != -1) {
            return ans;
        }

        if (s == 1) {
            int one = (act[0][i] + act[0][i - 1] + act[0][i + 1] + 1) / 3 + (act[1][i] + act[1][i + 1] + act[1][i + 2] + 1) / 3;
            int two = (act[0][i] + act[0][i - 1] + act[1][i] + 1) / 3;

            return ans = max(one + dp(i + 3, s), two + dp(i + 1, 0));
        }

        if (s == 2) {
            int one = (act[1][i] + act[1][i - 1] + act[1][i + 1] + 1) / 3 + (act[0][i] + act[0][i + 1] + act[0][i + 2] + 1) / 3;
            int two = (act[1][i] + act[1][i - 1] + act[0][i] + 1) / 3;

            return ans = max(one + dp(i + 3, s), two + dp(i + 1, 0));
        }

        int one = (act[0][i] + act[1][i] + act[1][i + 1] + 1) / 3;
        int two = (act[1][i] + act[0][i] + act[0][i + 1] + 1) / 3;
        int three = (act[0][i] + act[0][i + 1] + act[0][i + 2] + 1) / 3 + (act[1][i] + act[1][i + 1] + act[1][i + 2] + 1) / 3;

        return ans = max({one + dp(i + 2, 1), two + dp(i + 2, 2), three + dp(i + 3, 0)});
    };

    cout << dp(0, 0) << '\n';
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    pre();

    int t;
    (TEST && cin >> t) || (t = 1);
    while (t--) {
        solve();
    }
}