#include<bits/stdc++.h>

 using namespace std;

 #define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout);

 #define LL long long

 #define ULL unsigned LL

 #define fi first

 #define se second

 #define pb push_back

 #define lson l,m,rt<<1

 #define rson m+1,r,rt<<1|1

 #define max3(a,b,c) max(a,max(b,c))

 #define min3(a,b,c) min(a,min(b,c))

 typedef pair<int,int> pll;

 const LL INF = 0x3f3f3f3f3f3f3f3f;

 const int inf = 0x3f3f3f3f;

 const LL mod =  (int)1e9+;

 const int N = ;

 const int M = ;

 double eps = 1e-;

 int head[N], deep[N], cur[N];

 int u[M], v[M];

 int vis[N], d[N];

 double w[M]; int to[M], nx[M];

 int n, m, tot;

 int a[N];

 void add(int u, int v,double val){

     w[tot]  = val; to[tot] = v;

     nx[tot] = head[u]; head[u] = tot++;

     w[tot]  = ; to[tot] = u;

     nx[tot] = head[v]; head[v] = tot++;

 }

 int bfs(int s, int t){

     queue<int> q;

     memset(deep, , sizeof(int)*(n+));

     q.push(s);

     deep[s] = ;

     while(!q.empty()){

         int u = q.front();

         q.pop();

         for(int i = head[u]; ~i; i = nx[i]){

             if(w[i] >  && deep[to[i]] == ){

                 deep[to[i]] = deep[u] + ;

                 q.push(to[i]);

             }

         }

     }

     if(deep[t] > ) return ;

     return ;

 }

 double Dfs(int u, int t, double flow){

     if(u == t) return flow;

     for(int &i = cur[u]; ~i; i = nx[i]){

         if(deep[u] +  == deep[to[i]] && w[i] > ){

             double di = Dfs(to[i], t, min(w[i], flow));

             if(di > ){

                 w[i] -= di, w[i^] += di;

                 return di;

             }

         }

     }

     return ;

 }

 int Dinic(int s, int t){

     double ans = , tmp;

     while(bfs(s, t)){

         for(int i = ; i <= n+; i++) cur[i] = head[i];

         while(tmp = Dfs(s, t, INF)) ans += tmp;

     }

     return ans;

 }

 bool check(double x){

     memset(head, -, sizeof(int) * (n+));

     tot = ;

     int s = , t = n + ;

     for(int i = ; i <= m; i++){

         add(u[i], v[i], );

         add(v[i], u[i], );

     }

     for(int i = ; i <= n; i++){

         add(s, i, m);

         add(i, t, m+*x-d[i]);

     }

     return (m*n-Dinic(s,t))/2.0 >= 1e-;

 }

 int main(){

     int T;

     scanf("%d", &T);

     for(int _i = ; _i <= T; _i++){

         scanf("%d", &n);

         for(int i = ; i <= n; i++)scanf("%d", &a[i]);

         memset(d, , sizeof(int)*(n+));

         m = ;

         for(int i = ; i <= n; i++){

             for(int j = ; j < i; j++){

                 if(a[j] > a[i]){

                     d[i]++;

                     d[j]++;

                     m++;

                     u[m] = i;

                     v[m] = j;

                 }

             }

         }

         double l = , r = m,  mid;

         while(r - l >= eps){

             mid = (l+r)/;

             if(check(mid)) l = mid;

             else r = mid;

         }

         printf("Case #%d: %.12f\n", _i, l);

         //printf

     }

     return ;

 }