// Coded by hjxddl
#include <bits/stdc++.h>
#define ll long long
#define db double
const int N = 2e5 + 5;
int n, m;
int lowbit(int x) {
    return x & -x;
}
void change(int x, int k, std::vector<int> &t) {
    while (x <= n) {
        t[x] += k;
        x += lowbit(x);
    }
}
int query1(int x, std::vector<int> &t) {
    int ans = 0;
    while (x) {
        ans += t[x];
        x -= lowbit(x);
    }
    return ans;
}
int query(int l, int r, std::vector<int> &t) {
    return query1(r, t) - query1(l - 1, t);
}
void solve() {
    std::cin >> n >> m;
    std::vector<int> a(n + 5), t(n + 5);
    std::map<int, int> pos;
    for (int i = 1; i <= n; i++)
        std::cin >> a[i];
    int ans = 0;
    for (int i = 1; i <= n; i++) {
        if (pos.count(a[i]))
            change(pos[a[i]], -1, t);
        change(i, 1, t);
        if (i != n)
            ans = std::max(ans, query(1, i, t) - a[i + 1]);
        if (pos.count(a[i]))
            ans = std::max(ans, query(pos[a[i]] + 1, i - 1, t) - a[i]);
        pos[a[i]] = i;
        if (i == n) {
            for (int j = 1; j < n; j++) {
                if (j == pos[a[j]])
                    ans = std::max(ans, query(j + 1, n, t) - a[j]);
            }
        }
    }
    std::sort(a.begin() + 1, a.begin() + n + 1);
    int now = 1;
    for (int i = 1; i <= n; i++) {
        if (a[i] == now)
            now++;
    }
    ans = std::max(ans, query(1, n, t) - now);
    std::cout << ans << '\n';
}
int main() {
    std::ios::sync_with_stdio(0);
    std::cin.tie(0), std::cout.tie(0);
    int t = 1;
    std::cin >> t;
    while (t--) {
        solve();
    }
    std::cout << std::flush;
    // system("pause");
}