#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();
}