/*
Link: http://www.lightoj.com/volume_showproblem.php?problem=1241
*/

#include <bits/stdc++.h>

#define pii pair <int,int>
#define sc scanf
#define pf printf
#define Pi 2*acos(0.0)
#define ms(a,b) memset(a, b, sizeof(a))
#define pb(a) push_back(a)
#define MP make_pair
#define oo 1<<29
#define dd double
#define ll long long
#define EPS 10E-10
#define ff first
#define ss second
#define MAX 10000
#define SZ(a) (int)a.size()
#define getint(a) scanf("%d",&a)
#define loop(i,n) for(int i=0;i<n;i++)
#define TEST_CASE(t) for(int z=1;z<=t;z++)
#define PRINT_CASE printf("Case %d: ",z)
#define all(a) a.begin(),a.end()
#define intlim 2147483648
#define inf 1000000
#define rtintlim 46340
#define llim 9223372036854775808
#define rtllim 3037000499
#define ull unsigned long long
#define I int

using namespace std;

int main()
{
    ///freopen("in.txt","r",stdin);
    ///freopen("out.txt","w",stdout);
    int t,n;
    int ara[100];
    getint(t);
    TEST_CASE(t)
    {
        int temp=2;
        int ans=0;
        getint(n);
        loop(i,n)
        {
            getint(ara[i]);
            if(ara[i]>temp)
            {
                int a=ara[i]-temp;
                ans+=a/5;
                if(a%5)
                    ans++;
                temp=ara[i];
            }
        }
        PRINT_CASE;
        cout<<ans<<endl;
    }
    return 0;
}