#include <bits/stdc++.h>

using namespace std;

struct query {
    int l;
    int mex;
};

const int N = 5e5 + 10;
int n, m;
int a[N];
vector<int> pos[N];
vector<query> qs[N];
int fenw[N];
int lst[N];

void update(int x, int val) {
    for(int i = x; i <= n; i += (i & -i)) {
        fenw[i] += val;
    }
}

int get(int r) {
    int ans = 0;
    for(int i = r; i >= 1; i -= (i & -i)) {
        ans += fenw[i];
    }
    return ans;
}

int get(int l, int r) {
    return get(r) - get(l - 1);
}

void solve() {
    cin >> n >> m;
    for(int i = 1; i <= n; i++) {
        qs[i].clear();
        fenw[i] = 0;
        cin >> a[i];
        pos[a[i]].push_back(i);
    }
    for(int mex = 1; mex <= n + 1; mex++) {
        if(pos[mex].size() == 0) {
            qs[n].push_back({1, mex});
            continue;
        }
        qs[pos[mex][0] - 1].push_back({1, mex});
        for(int i = 1; i < pos[mex].size(); i++) {
            qs[pos[mex][i] - 1].push_back({pos[mex][i - 1] + 1, mex});
        }
        qs[n].push_back({pos[mex].back() + 1, mex});
    }
    int ans = 0;
    for(int r = 1; r <= n; r++) {
        if(lst[a[r]] > 0) update(lst[a[r]], -1);
        lst[a[r]] = r;
        update(lst[a[r]], 1);
        for(query q : qs[r]) {
            int l = q.l, mex = q.mex;
            if(l > r) continue;
            ans = max(ans, get(l, r) - mex);
        }
    }
    cout << ans << "\n";
    for(int i = 1; i <= n; i++) {
        pos[a[i]].clear();
        lst[a[i]] = 0;
    }
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    int t;
    cin >> t;
    while(t--) {
        solve();
    }
    return 0;
}