#include <bits/stdc++.h>

#define EPS 1e-6
#define MOD 1000000007
#define inf 0x3f3f3f3f
#define llinf 0x3f3f3f3f3f3f3f3f

#define fi first
#define se second
#define pb push_back
#define ende '\n'

#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define mset(x, y) memset(&x, (y), sizeof(x))

using namespace std; 

typedef long long ll;
typedef pair<int,int> ii;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);

  int t; cin >> t;
  for (int cas = 1; cas <= t; ++cas) {
    int n; cin >> n;
    vector<int> v(n);
    for (auto &i : v) cin >> i;

    vector<int> v1, v2;
    for (int i = 0; i < n; ++i)
      if (i % 2) v2.pb(v[i]);
      else v1.pb(v[i]);

    sort(all(v1));
    sort(all(v2));

    int j = 0;
    for (auto i : v1) {
      v[j] = i;
      j += 2;
    }

    j = 1;
    for (auto i : v2) {
      v[j] = i;
      j += 2;
    }

    int ans = -1;
    for (int i = 0; i < n - 1; ++i) {
      if (v[i] > v[i+1]) {
        ans = i;
        break;
      }
    }
    cout << "Case #" << cas << ": ";
    if (ans == -1) cout << "OK" << ende;
    else cout << ans << ende;
  }

  return 0;
}