#include <cstdio>
#include <cstring>
#include <stack>
#include <vector>
#include <algorithm>
#include <queue>
#include <map>
#include <string>
#include <cmath>

#define ll long long
int const N = 100005;
int const M = 205;
int const INF = 0x7fffffff;
int const mod = 100007;

using namespace std;

int T,ccnt;
int n;
int a[N];
int cnt[N];
int ans;

void cal(int x)
{
    int i;
    for(i=1;i*i<=x;i++){
        if(x%i==0){
            cnt[i]++;cnt[x/i]++;
        }
        if(i*i==x){
            cnt[i]--;
        }
    }
}

void ini()
{
    scanf("%d",&n);
    int i;
    memset(cnt,0,sizeof(cnt));
    for(i=1;i<=n;i++){
        scanf("%d",&a[i]);
        cal(a[i]);
    }
}

void solve()
{
    int i;
    for(i=N-5;i>=1;i--){
        if(cnt[i]>=2){
            ans=i;break;
        }
    }
}

void out()
{
    printf("Case #%d: %d\n",ccnt,ans);
}

int main()
{
    //freopen("data.in","r",stdin);
    scanf("%d",&T);
    for(ccnt=1;ccnt<=T;ccnt++)
   // while(T--)
    //while(scanf("%d%d",&n,&m)!=EOF)
    {
        ini();
        solve();
        out();
    }

    return 0;
}