#include <stdio.h>

int gcd(int a, int b){
	return a==0?b:gcd(b%a,a);
} 

void insertionSort(int arr[], int n){ 
   int key, j; 
   for(int i=1;i<n;i++){ 
       key = arr[i]; 
       j = i-1; 
       while (j>=0 && arr[j]>key){ 
           arr[j+1] = arr[j]; 
           j--; 
       } 
       arr[j+1] = key; 
   } 
} 

int findGCD(int arr[], int n){
	int high=0;
	for(int i=n-1;i>=0;i--){
		for(int j=i-1;j>=0;j--){
			int temp = gcd(arr[i], arr[j]);
			if(arr[j]<high){
				break;
			}else if(temp>high){
				high = temp;
			}
		}
	}
	return high;
}

int main(){ 
	int tc;
	scanf("%d", &tc);
	for(int i=1;i<=tc;i++){
		int n, product=1, high=0, check;
		scanf("%d", &n);
		int data[n];
		for(int j=0;j<n;j++){
			scanf("%d", &data[j]);
		}
		insertionSort(data, n);
		printf("Case #%d: %d\n", i, findGCD(data, n));
	}
	return 0; 
}