#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;
typedef pair<int, int> PII;
const int N = 200000 + 10, M = 2e5 + 10;
//#define p first
//#define d second
mt19937 rnd(time(0));
int qpow(int a,int b,int m)
{
    int res=1;
    while(b)
    {
        if(b&1) res=res*a%m;
        b>>=1;
        a=a*a%m;
    }
    return res;
}
int mod;
int a[N];
int n;
int check(int ll,int rr)
{
    int p=a[rr]*qpow(a[ll],mod-2,mod)%mod;
    int cnt=2;
    int now=ll;
    for(int i=ll-1;i>=1;i--){
        if(p*a[i]%mod==a[now]){
            cnt++;
            now=i;
        }
    }
    now=rr;
    for(int i=rr+1;i<=n;i++){
        if(a[now]*p%mod==a[i]){
            cnt++;
            now=i;
        }
    }
    return cnt;

}

void solve(){
    cin>>n>>mod;
    for(int i=1;i<=n;i++)
    {
        cin>>a[i];
    }
    int len=max((n+299)/300,(int)2);
    int ok=0;
    for(int i=1;i<=n;i+=len){
        int l=i,r=min(n,i+len-1);
        int p=min(r-1,rnd()%len+l);
        int ne=min(r,p+1);
        ok=max(ok,check(p,ne));
        ne=min(n,p+2);
        ok=max(ok, check(p,ne));
        ne=min(n,p+3);
        ok=max(ok, check(p,ne));
        ne=min(n,p+4);
        ok=max(ok, check(p,ne));
        ne=min(n,p+5);
        ok=max(ok, check(p,ne));
    }
    if(ok>=(n+1)/2){
        cout<<ok<<"\n";
    }else{
        cout<<-1<<'\n';
    }
}

signed main(){
    ios::sync_with_stdio(false);cin.tie(0);
//    srand(time(0));
    int _ = 1;
    cin >> _;
    while(_--) solve();
    return 0;
}

answer.code: In function ‘void solve()’:
answer.code:56:18: error: no matching function for call to ‘min(long long int, long long unsigned int)’
   56 |         int p=min(r-1,rnd()%len+l);
      |               ~~~^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_algobase.h:230:5: note: candidate: ‘template<class _Tp> constexpr const _Tp& std::min(const _Tp&, const _Tp&)’
  230 |     min(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/11/bits/stl_algobase.h:230:5: note:   template argument deduction/substitution failed:
answer.code:56:18: note:   deduced conflicting types for parameter ‘const _Tp’ (‘long long int’ and ‘long long unsigned int’)
   56 |         int p=min(r-1,rnd()%len+l);
      |               ~~~^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/11/bits/specfun.h:45,
                 from /usr/include/c++/11/cmath:1927,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:41,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_algobase.h:278:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr const _Tp& std::min(const _Tp&, const _Tp&, _Compare)’
  278 |     min(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/11/bits/stl_algobase.h:278:5: note:   template argument deduction/substitution failed:
answer.code:56:18: note:   deduced conflicting types for parameter ‘const _Tp’ (‘long long int’ and ‘long long unsigned int’)
   56 |         int p=min(r-1,rnd()%len+l);
      |               ~~~^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/11/algorithm:62,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_algo.h:3449:5: note: candidate: ‘template<class _Tp> constexpr _Tp std::min(std::initializer_list<_Tp>)’
 3449 |     min(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/11/bits/stl_algo.h:3449:5: note:   template argument deduction/substitution failed:
answer.code:56:18: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘long long int’
   56 |         int p=min(r-1,rnd()%len+l);
      |               ~~~^~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/11/algorithm:62,
                 from /usr/include/x86_64-linux-gnu/c++/11/bits/stdc++.h:65,
                 from answer.code:1:
/usr/include/c++/11/bits/stl_algo.h:3455:5: note: candidate: ‘template<class _Tp, class _Compare> constexpr _Tp std::min(std::initializer_list<_Tp>, _Compare)’
 3455 |     min(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/11/bits/stl_algo.h:3455:5: note:   template argument deduction/substitution failed:
answer.code:56:18: note:   mismatched types ‘std::initializer_list<_Tp>’ and ‘long long int’
   56 |         int p=min(r-1,rnd()%len+l);
      |               ~~~^~~~~~~~~~~~~~~~~