#include <bits/stdc++.h>
#define ppc __builtin_popcount
#define IOS ios::sync_with_stdio(0), cin.tie(0)
#define int long long
#define endl '\n'
#define lowbit(x) (x) & (-x)
#define pii pair<int, int>
#define all(s) s.begin(), s.end()
#define ls(x) (x << 1)
#define rs(x) (x << 1 | 1)
#define here system("pause")
using namespace std;
template <class T>
inline void read(T &x)
{
    x = 0;
    char c = getchar();
    bool f = 0;
    for (; !isdigit(c); c = getchar())
        f ^= (c == '-');
    for (; isdigit(c); c = getchar())
        x = (x << 3) + (x << 1) + (c ^ 48);
    x = f ? -x : x;
}
template <class T>
inline void write(T x)
{
    if (x < 0)
        putchar('-'), x = -x;
    if (x < 10)
        putchar(x + 48);
    else
        write(x / 10), putchar(x % 10 + 48);
}

const int N = 2e6 + 5;
const int INF = 1e18;
int mod;

inline int pow(int a, int b, int p)
{
    int res = 1 % p;
    while (b)
    {
        if (b & 1)
            res = res * a % p;
        a = a * a % p, b >>= 1;
    }
    return res;
}
inline int inv(int a, int p) { return pow(a, p - 2, p) % p; }
int b[N]={0};

// 714285720
int n;
int flag=0;
int search(int idx, int num)
{ // cout<<idx<<"yes"<<endl;
    int cntt = 0;
    if (idx == n)
        return 0;
    int p1 = (b[idx + 1] * inv(b[idx], mod) )% mod;
    cntt += 2;
    for (int i = idx - 1; i >= 1; i--)
    { // if(idx==2)cout<<b[i] * p1 % mod<<"num="<<num<<endl;
        if ((b[i] * p1) % mod == num)
        {
            cntt++;
            num = b[i];
        }
    }
    num = b[idx + 1];
    for (int i = idx + 2; i <= n; i++)
    { // if(idx==2)cout<<num * p1 % mod<<"num="<<num<<endl;
        if ((num * p1) % mod == b[i])
        {
            cntt++;
            num = b[i];
        }
    }
    if (idx == n - 1)
    {
        if (cntt >= ceil(n * 1.0 / 2))
            flag = max(flag,cntt);
        return cntt >= ceil(n * 1.0 / 2);
    }
    int cnttt = 0;
    num = b[idx];
    int p2 = b[idx + 2] * inv(b[idx], mod) % mod;
    cnttt += 2;
    for (int i = idx - 1; i >= 1; i--)
    { // if(idx==2)cout<<b[i] * p1 % mod<<"num="<<num<<endl;
        if ((b[i] * p2) % mod == num)
        {
            cnttt++;
            num = b[i];
        }
    }
    num = b[idx + 2];
    for (int i = idx + 3; i <= n; i++)
    { // if(idx==2)cout<<num * p1 % mod<<"num="<<num<<endl;
        if ((num * p2)% mod == b[i])
        {
            cnttt++;
            num = b[i];
        }
    }

    cntt = max(cntt, cnttt);
    //if (cntt >= (n * 1.0 / 2))
        flag = max(flag,cntt);
    return cntt >= (n * 1.0 / 2);
}
void scan(int l, int r)
{
  
    if (l >= r)
        return;
    queue<pii> q;
    q.push({1, n});
    int cnt = 0;
    while (!q.empty() && cnt <= 400)
    {
        pii c = q.front();
        cnt++;
        q.pop();
        int mid = (c.first + c.second) >> 1;
       
            q.push({mid, r});
            q.push({l, mid});
        
        // else
        //     return;
        // if (flag != 0)
        //     return;
        // if (!search(r, b[r]))
        //     scan(mid + 1, r - 1);
    }
    return;
}
signed main()
{
    IOS;
    int t;
    cin >> t;
    // cout<<inv(7,1000000007)*5<<endl;
    // cout<<(714285720ll*7)%1000000007;
    while (t--)
    {

        cin >> n >> mod;
        for (int i = 1; i <= n; i++)
            cin >> b[i];
        if (n == 2)
        {
            cout << "2" << endl;
            continue;
        }
        flag = 0;
        if (n <= 40)
        {
            for (int i = 1; i <= n; i++)
                search(i, b[i]);
        }
        else
            scan(1, n);
        cout << ((flag <(n*1.0/2)) ? -1 : flag) << endl;
    }
}