#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
const long long MOD = 998244353;
// using mint = modint1000000007;
// const long long MOD = 1000000007;
// using mint = modint;//mint::set_mod(MOD);

#include <bits/stdc++.h>
#define rep(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
#define repeq(i, a, b) for (ll i = (ll)(a); i <= (ll)(b); i++)
#define repreq(i, a, b) for (ll i = (ll)(a); i >= (ll)(b); i--)
#define endl '\n'  // fflush(stdout);
#define cYes cout << "Yes" << endl
#define cNo cout << "No" << endl
#define sortr(v) sort(v, greater<>())
#define pb push_back
#define pob pop_back
#define mp make_pair
#define mt make_tuple
#define FI first
#define SE second
#define ALL(v) (v).begin(), (v).end()
#define INFLL 3000000000000000100LL
#define INF 1000000100
#define PI acos(-1.0L)
#define TAU (PI * 2.0L)

using namespace std;

typedef long long ll;
typedef pair<ll, ll> Pll;
typedef tuple<ll, ll, ll> Tlll;
typedef vector<int> Vi;
typedef vector<Vi> VVi;
typedef vector<ll> Vl;
typedef vector<Vl> VVl;
typedef vector<VVl> VVVl;
typedef vector<Tlll> VTlll;
typedef vector<mint> Vm;
typedef vector<Vm> VVm;
typedef vector<string> Vs;
typedef vector<double> Vd;
typedef vector<char> Vc;
typedef vector<bool> Vb;
typedef vector<Pll> VPll;
typedef priority_queue<ll> PQl;
typedef priority_queue<ll, vector<ll>, greater<ll>> PQlr;

/* inout */
ostream &operator<<(ostream &os, mint const &m) {
    os << m.val();
    return os;
}
istream &operator>>(istream &is, mint &m) {
    long long n;
    is >> n, m = n;
    return is;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    int n = v.size();
    rep(i, 0, n) { os << v[i] << " \n"[i == n - 1]; }
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<vector<T>> &v) {
    int n = v.size();
    rep(i, 0, n) os << v[i];
    return os;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, pair<T, S> const &p) {
    os << p.first << ' ' << p.second;
    return os;
}
template <typename T, typename S>
ostream &operator<<(ostream &os, const map<T, S> &ma) {
    for (auto &[key, val] : ma) {
        os << key << ':' << val << '\n';
    }
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &st) {
    auto itr = st.begin();
    for (int i = 0; i < (int)st.size(); i++) {
        os << *itr << (i + 1 != (int)st.size() ? ' ' : '\n');
        itr++;
    }
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, multiset<T> &st) {
    auto itr = st.begin();
    for (int i = 0; i < (int)st.size(); i++) {
        os << *itr << (i + 1 != (int)st.size() ? ' ' : '\n');
        itr++;
    }
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, queue<T> q) {
    while (q.size()) {
        os << q.front();
        q.pop();
        os << " \n"[q.empty()];
    }
    return os;
}
template <typename T>
ostream &operator<<(ostream &os, stack<T> st) {
    vector<T> v;
    while (st.size()) {
        v.push_back(st.top());
        st.pop();
    }
    reverse(ALL(v));
    os << v;
    return os;
}
template <class T, class Container, class Compare>
ostream &operator<<(ostream &os, priority_queue<T, Container, Compare> pq) {
    vector<T> v;
    while (pq.size()) {
        v.push_back(pq.top());
        pq.pop();
    }
    os << v;
    return os;
}
template <typename T>
istream &operator>>(istream &is, vector<T> &v) {
    for (T &in : v) is >> in;
    return is;
}
template <typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) {
    is >> p.first >> p.second;
    return is;
}

/* useful */
template <typename T>
int SMALLER(vector<T> &a, T x) {
    return lower_bound(a.begin(), a.end(), x) - a.begin();
}
template <typename T>
int orSMALLER(vector<T> &a, T x) {
    return upper_bound(a.begin(), a.end(), x) - a.begin();
}
template <typename T>
int BIGGER(vector<T> &a, T x) {
    return a.size() - orSMALLER(a, x);
}
template <typename T>
int orBIGGER(vector<T> &a, T x) {
    return a.size() - SMALLER(a, x);
}
template <typename T>
int COUNT(vector<T> &a, T x) {
    return upper_bound(ALL(a), x) - lower_bound(ALL(a), x);
}
template <typename T, typename S>
bool chmax(T &a, S b) {
    if (a < b) {
        a = b;
        return 1;
    }
    return 0;
}
template <typename T, typename S>
bool chmin(T &a, S b) {
    if (a > b) {
        a = b;
        return 1;
    }
    return 0;
}
template <typename T>
void press(T &v) {
    v.erase(unique(ALL(v)), v.end());
}
template <typename T>
vector<int> zip(vector<T> a) {
    int n = a.size();
    pair<T, int> p[n];
    vector<int> v(n);
    for (int i = 0; i < n; i++) p[i] = make_pair(a[i], i);
    sort(p, p + n);
    int w = 0;
    for (int i = 0; i < n; i++) {
        if (i && p[i].first != p[i - 1].first) w++;
        v[p[i].second] = w;
    }
    return v;
}
template <typename T>
vector<T> vis(vector<T> &v) {
    vector<T> S(v.size() + 1);
    rep(i, 1, S.size()) S[i] += v[i - 1] + S[i - 1];
    return S;
}
template <typename T>
T ceil_div(T a, T b) {
    if (b < 0) a = -a, b = -b;
    return (a >= 0 ? (a + b - 1) / b : a / b);
}
template <typename T>
T floor_div(T a, T b) {
    if (b < 0) a = -a, b = -b;
    return (a >= 0 ? a / b : (a - b + 1) / b);
}
ll dtoll(double d, int g) { return round(d * pow(10, g)); }

const double EPS = 1e-10;

void init() {
    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);
    cout.precision(12);
    cout << fixed;
}

// do {} while (next_permutation(ALL(vec)));

/********************************** START **********************************/

void sol();

int main() {
    init();
    int q = 1;
    cin >> q;
    while (q--) sol();
    return 0;
}

/********************************** SOLVE **********************************/

struct Mo {
    int n;
    vector<pair<int, int>> lr;

    explicit Mo(int n) : n(n) {}

    void add(int l, int r) { /* [l, r) */
        lr.emplace_back(l, r);
    }

    template <typename AL, typename AR, typename EL, typename ER, typename O>
    void build(const AL &add_left, const AR &add_right, const EL &erase_left,
               const ER &erase_right, const O &out) {
        int q = (int)lr.size();
        int bs = n / min<int>(n, sqrt(q));
        vector<int> ord(q);
        iota(begin(ord), end(ord), 0);
        sort(begin(ord), end(ord), [&](int a, int b) {
            int ablock = lr[a].first / bs, bblock = lr[b].first / bs;
            if (ablock != bblock) return ablock < bblock;
            return (ablock & 1) ? lr[a].second > lr[b].second
                                : lr[a].second < lr[b].second;
        });
        int l = 0, r = 0;
        for (auto idx : ord) {
            while (l > lr[idx].first) add_left(--l);
            while (r < lr[idx].second) add_right(r++);
            while (l < lr[idx].first) erase_left(l++);
            while (r > lr[idx].second) erase_right(--r);
            out(idx);
        }
    }

    template <typename A, typename E, typename O>
    void build(const A &add, const E &erase, const O &out) {
        build(add, add, erase, erase, out);
    }

    /*
    Mo mo(n);
    auto add = [&](int i) { now += a[i]; };
    auto erase = [&](int i) { now -= a[i]; };
    auto out = [&](int i) { ans[i] = now; };
    mo.add(L, R); // [L,R)
    mo.build(add, erase, out);
    */
};

void sol() {
    int n, x;
    cin >> n >> x;
    vector<int> l(n), r(n);
    Mo mo(n);
    rep(i, 0, n) {
        cin >> l[i] >> r[i];
        mo.add(l[i], r[i]);
    }
    vector<int> ans;
    int sm = 0;
    auto add = [&](int i) { sm += i; };
    auto erase = [&](int i) { sm += i; };
    auto out = [&](int i) {
        ans.pb(i);
        return;
    };
    mo.build(add, erase, out);
    cout << ans.size() << endl;
    rep(i, 0, n) cout << l[ans[i]] << " " << r[ans[i]] << endl;
}