#include<cstdio>
#include<algorithm>
#include<vector>
#include<cstring>
#include<cassert>

using namespace std;

#define MEM(a,b) memset(a,(b),sizeof(a))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
#define MIN(a,b) ((a) < (b) ? (a) : (b))

#define MP make_pair
#define pb push_back

#define maxn 100000
#define maxd 100000
#define maxt 10

typedef long long  LL;
typedef pair<int,int> pi;
typedef pair<int,pi> pii;


//vector<int> divs[maxd+1]

int arr[maxn+5];

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


int main()
{
   int i,j,k,n,q,T;

 

   scanf("%d",&T);
   assert(T>=1 && T<=maxn);

  while(T--)
  {
      scanf("%d",&n);
       assert(n>=2 && n<=maxt);

       int g;

       for(i=0;i<n;i++)
       {
           scanf("%d",&arr[i]);
           assert(arr[i]>=1 && arr[i]<=maxn);
           if(!i) g=arr[i];
           else g=gcd(g,arr[i]);
       }

       int ans = g==1 ? n : -1; // if the gcd of all number is not 1, no subarray has gcd=1
        printf("%d\n",ans);

  }




	return 0;
}