#include <bits/stdc++.h>
using namespace std;

#define ll long long
typedef vector<int> vi;
typedef pair<int,int> ii;
// typedef long long ll;
typedef vector<ll> vI;
typedef pair<ll,ll> II;

#define INT_MAX 2147483647
#define M 1000000
#define pb push_back
#define ppb pop_back
#define mp make_pair
#define F first
#define S second
#define forl(i,a,b) for((long long int) i=a;i<b;++i)
#define nforl(i,a,b) for((long long int) i=a;i>=b;--i)
#define fori(i,a,b) for(int i=a;i<b;i++)
#define nfori(i,a,b) for(int i=a;i>=b;--i)
const int mod = 1e9+7;
long long int gcd(long long int a,long long int b){
    if(b==0) return a;
    else return gcd(b,a%b);
}

int compare(const void *a, const void *b){
    const ll* x=(ll*) a;
    const ll* y=(ll*) b;

    if(*x>*y) return 1;         // qsort(a,n,sizeof(ll),compare);
    else if(*x<*y) return -1;
    return 0;
}

void solve(){
	int n,x;
	scanf("%d%d",&n,&x);
	int arr[n];
	ll sum=0,sum1=0;
	for(int i=0;i<n;i++ ){ scanf("%d",&arr[i]); sum+=arr[i]; if(arr[i]%x==0) sum1++;  }
	if(sum1==n){
			printf("-1\n"); return;
	}
	if(sum%x!=0) {
		printf("%d\n",n); return;
	}
	int start=-1,end=-1;
	for(int i=0;i<n;i++){
		if(arr[i]%x!=0){ start=n-(i+1); break;  }
	}
	for(int i=n-1;i>=0;i--){
		if(arr[i]%x!=0){ end=i; 	 break;     }
	}
	int res=max(start,end);

	cout<<res<<endl;
	return;
}

int main(){
 	ios_base::sync_with_stdio(false), cin.tie(nullptr);
    int t,z=1;
    scanf("%d",&t);
    while(z<=t){
        solve(); z++;
    }
    return 0;
}