#include "bits/stdc++.h"
using namespace std;

int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);

  int tt;
  cin >> tt;
  while(tt--) {
    int n;
    string s, t;
    cin >> n >> s >> t;
    vector<bool> changed(n);
    for (int i =0; i < n; i++) {
      changed[i] = s[i] != t[i];
    }
    vector<pair<int, int>> runs;
    int l = -1, r = -1;
    for (int i =0; i < n; i++) {
      if (changed[i]) {
        if (l == -1) l = i;
      } else {
        if (l != -1) {
          runs.push_back({l, i-1});
        }
        l = r = -1;
      }
    }
    if (l != -1) {
      runs.push_back({l, n-1});
    }
    if (runs.size() == 0) {
      cout << (int64_t(n) * (n-1))/2 << '\n';
    } else if (runs.size() == 2){
      cout << 6 << '\n';
    } else if (runs.size() == 1) {
      auto& [l, r] = runs[0];
      int64_t ans =  2 * (l + n - 1 -r) + 2*(r-l);
      cout << ans << '\n';
    } else {
      cout << 0 << '\n';
    }
  }
}