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

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdi = pair<double, int>;
using pdd = pair<double, double>;
using ull = unsigned long long;
using LL = __int128_t;

#define ppc(x) __builtin_popcount(x)
#define clz(x) __builtin_clz(x)

bool Mbe;

constexpr int mod = 1e9 + 7;
void addt(int &x, int y) {
  x += y, x >= mod && (x -= mod);
}
int add(int x, int y) {
  return x += y, x >= mod && (x -= mod), x;
}

// ---------- templates above ----------

int n;
string s, t;
void solve() {
  cin >> n >> s >> t;
  int st = -1, cnt = 0;
  for(int i = 0; i < n; i++) {
    if(s[i] != t[i]) {
      if(st == -1) st = i;
    }
    else {
      if(st != -1) cnt++, st = -1;
    }
  }
  if(st != -1) cnt++;
  if(cnt > 2) {
    cout << "0\n";
    return;
  }
  if(cnt == 0) {
    cout << 1ll * n * (n + 1) / 2 << "\n";
    return;
  }
  if(cnt == 2) {
    cout << 6 << "\n";
    return;
  }
  cout << 2 * (n - 1) << "\n";
}

bool Med;
signed main() {
  fprintf(stderr, "%.3lf MB\n", (&Mbe - &Med) / 1048576.0);
  // ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  #ifdef ALEX_WEI
    FILE* IN = freopen("1.in", "r", stdin);
    FILE* OUT = freopen("1.out", "w", stdout);
  #endif
  int T = 1;
  cin >> T;
  while(T--) solve();
  fprintf(stderr, "%.3lf ms\n", 1e3 * clock() / CLOCKS_PER_SEC);
  return 0;
}

/*
g++ a.cpp -o a -std=c++14 -O2 -DALEX_WEI
*/