#include <bits/stdc++.h>

using namespace std;

void solve() {

    int n, x; cin >> n >> x;

    int a[n] = {}, sum = 0;

    for (int i = 0; i < n; i++) {

        cin >> a[i];

        a[i] %= x, sum += a[i];

    }

    if (sum == 0)

        cout << -1 << "\n";

    else if (sum % x)

        cout << n << "\n";

    else {

        int l = 0, r = n - 1;

        while (a[l] == 0) ++l;

        while (a[r] == 0) --r;

        cout << max(n - 1 - l, r) << "\n";

    }

}

int main() {

    int t; cin >> t;

    while (t--) solve();

}