#include <bits/stdc++.h>
#define mp make_pair
using namespace std;

long long t, n, m, I, a[500010], la[500010], rez, g, tree[1000020];
vector<int> v[500010];
vector<pair<pair<int, int>, int> > rl;
map<int, bool> cp;

long long sum(int l, int r) {
    l+=g;
    r+=g;
    long long s=0;
    while(r-l>=0) {
        if(l%2) {
            s+=tree[l];
            l++;
        }
        if(r%2==0) {
            s+=tree[r];
            r--;
        }
        l/=2;
        r/=2;
    }
    return s;
}

void update(int i, int x) {
    i+=g;
    tree[i]=x;
    i/=2;
    while(i>0) {
        tree[i]=tree[2*i]+tree[2*i+1];
        i/=2;
    }
}

int main() {
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    cin>>t;
    while(t--) {
        cin>>n>>m;
        cp.clear();
        rez=-5;
        g=1;
        while(g<=n) g*=2;
        g--;
        for(int i=1; i<=n; i++) {
            cin>>a[i];
            cp[a[i]]=true;
            v[a[i]].push_back(i);
            update(i, 0);
        }
        for(auto i:cp) {
            la[i.first]=0;
            sort(v[i.first].begin(), v[i.first].end());
            v[i.first].push_back(n+1);
        }
        for(int mex=1; mex<=m; mex++) {
            if(v[mex].empty()) {
                rl.push_back(mp(mp(n, 1), mex));
                break;
            }
            if(v[mex][0]-1>=1) rl.push_back(mp(mp(v[mex][0]-1, 1), mex));
            for(int i=1; i<v[mex].size(); i++) {
                if(v[mex][i]-1>=v[mex][i-1]+1) rl.push_back(mp(mp(v[mex][i]-1, v[mex][i-1]+1), mex));
            }
        }
        sort(rl.begin(), rl.end());
        I=0;
        for(int R=1; R<=n; R++) {
            update(la[a[R]], 0);
            update(R, 1);
            la[a[R]]=R;
            while(I<rl.size()&&rl[I].first.first==R) {
                rez=max(rez, sum(rl[I].first.second, rl[I].first.first)-rl[I].second);
                I++;
            }
        }
        rl.clear();
        cout<<rez<<'\n';
        for(auto i:cp) {
            v[i.first].clear();
        }
    }
}