E innopolis

//나는 가상 소녀들에게 큰 호감이 있습니다.

#include <iostream>
#include <cmath>
#include <algorithm>
#include <stdio.h>
#include <cstring>
#include <string>
#include <cstdlib>
#include <vector>
#include <bitset>
#include <map>
#include <chrono>
#include <functional>
#include <unordered_set>
#include <unordered_map>
#include <numeric>
#include <queue>
#include <ctime>
#include <stack>
#include <set>
#include <list>
#include <deque>
#include <iomanip>
#include <sstream>
#include <fstream>
#include <stdarg.h>
#include <utility>

using namespace std;

#define pb push_back
#define mp make_pair
#define ll long long
#define ull unisgned long long
#define ld long double
#define all(a) a.begin(), a.end()
#define SORT(a) sort(all(a))
#define pii pair<int, int>
#define tii triple<int, int, int>
#define e 1e-7
#define PI acos(-1)
#define sz(a) (int)(a.size())
#define inf 1e17
#define vi vector<int>
#define F first
#define S second
#define rng(x) for(int _ = 0; _ < (x); _++)
#define rngi(i, x) for(int i = 0; i < (x); i++)
#define rngsi(s, i, x) for(int i = (s); i <(x); i++)
#define int long long
#define problem "a"

template<typename A, typename B, typename C>
struct triple {
    A X;
    B Y;
    C Z;
    triple(A a = 0, B b = 0, C c = 0) :X(a), Y(b), Z(c) {}
};
template<typename A, typename B, typename C>
triple<A, B, C> make_triple(A a = 0, B b = 0, C c = 0) {
    return triple<A, B, C>(a, b, c);
}
template<typename A, typename B, typename C>
bool operator<(const triple<A, B, C>& a, const triple<A, B, C>& b) {
    if (a.X != b.X)
        return a.X < b.X;
    if (a.Y != b.Y)
        return a.Y < b.Y;
    return a.Z < b.Z;
}
template<typename T, typename SS>
ostream& operator<<(ostream& ofs, const pair<T, SS>& p) {
    ofs << "( " << p.F << " , " << p.S << " )";
    return ofs;
}
template<typename T>
void print(T a) {
    for (auto i : a)
        cout << i << ' ';
    cout << '\n';
}
template<typename T>
T max(T a, T b, T c) {
    return max(a, max(b, c));
}
template<typename T>
T min(T a, T b, T c) {
    return min(a, min(b, c));
}
template<typename T, typename D>
D min(T a) {
    return *min_element(all(a));
}
template<typename T, typename D>
D max(T a) {
    return *max_element(all(a));
}
struct custom_hash {
    static uint64_t splitmix64(uint64_t x) {
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
void solve() {
    int n; cin >> n;
    vector<pii> a(n);
    rngi(i, n) cin >> a[i].first >> a[i].second;
    int ans = 4;
    rng(2) {
        vi xx, yy;
        rngi(i, n) xx.push_back(a[i].first), yy.push_back(a[i].second);
        SORT(xx); xx.erase(unique(all(xx)), xx.end());
        SORT(yy); yy.erase(unique(all(yy)), yy.end());
        vector<vi> mx(n), my(n);
        vector<pii> b;
        rngi(i, n) {
            int x = a[i].first, y = a[i].second;
            x = lower_bound(all(xx), x) - xx.begin();
            y = lower_bound(all(yy), y) - yy.begin();
            b.push_back({ x,y });
            mx[x].push_back(y);
        }
        rngi(i, n) SORT(mx[i]), SORT(my[i]);
        int lim = sqrt(n) + 2;
        vector<pii> c;
        rngi(i, n)
            if (sz(mx[i]) < lim)for (auto v : mx[i]) c.push_back({ i, v });
        for (auto p : c) my[p.second].push_back(p.first);
        rngi(i, n) SORT(my[i]);
        vi cnt(n);
        rngi(i, n) {
            for (auto x : my[i]) for (auto d : mx[x]) if (d > i) {
                cnt[d]++; if (cnt[d] == 2)return void(cout << "0\n");
            }
            for (auto x : my[i]) for (auto d : mx[x]) if (d > i) {
                cnt[d]--;
            }
        }
        vector<vi> ptr(n);
        cnt.assign(n, 0);
        rngi(i, n) if (sz(mx[i]) >= lim) for (auto d : mx[i]) ptr[d].push_back(i);
        rngi(i, n) {
            if (sz(mx[i]) < lim) for (auto d : mx[i]) for (auto t : ptr[d]) { cnt[t]++;  if (cnt[d] == 2)return void(cout << "0\n"); }

            if (sz(mx[i]) < lim) for (auto d : mx[i]) for (auto t : ptr[d]) { cnt[t]--; }
        }
        rngi(i, n) swap(a[i].first, a[i].second);
    }

    vi xx, yy;
    rngi(i, n) xx.push_back(a[i].first), yy.push_back(a[i].second);
    SORT(xx); xx.erase(unique(all(xx)), xx.end());
    SORT(yy); yy.erase(unique(all(yy)), yy.end());
    vi cx(n), cy(n);
    vector<pii> b;
    vector< vi > mx(n), my(n);
    rngi(i, n) {
        int x = a[i].first, y = a[i].second;
        x = lower_bound(all(xx), x) - xx.begin();
        y = lower_bound(all(yy), y) - yy.begin();
        b.push_back({ x,y });
        cx[x]++; cy[y]++;
        mx[x].push_back(y);
        my[y].push_back(x);
    }
    vi d(n);
    rngi(i, n) if (cx[i] > 1)  for (auto v : mx[i]) {
        d[v]++; if (d[v] == 2) return void(cout << "1\n");
    }
    d.assign(n, 0);
    rngi(i, n) if (cy[i] > 1)  for (auto v : my[i]) {
        d[v]++; if (d[v] == 2) return void(cout << "1\n");
    }
    int aa = 0;
    rngi(i, n) if (cx[i] > 1) aa++;
    if(aa > 1)return void(cout << "2\n");
    aa = 0;

    rngi(i, n) if (cy[i] > 1) aa++;
    if (aa > 1)return void(cout << "2\n");
    rngi(i, n) if (cx[b[i].first] > 1 && cy[b[i].second] > 1)return void(cout << "2\n");


    rngi(i, n) if((cx[b[i].first] > 1 || cy[b[i].second] > 1) && (cx[b[i].first] != n && cy[b[i].second] != n))return void(cout << "3\n");
    cout << 4 << '\n';
};
void working() {
    int n; cin >> n;
    vector<pii> a(n);
    rngi(i, n) cin >> a[i].first >> a[i].second;
    int ans = 4;
    rng(2) {
        vi xx, yy;
        rngi(i, n) xx.push_back(a[i].first), yy.push_back(a[i].second);
        SORT(xx); xx.erase(unique(all(xx)), xx.end());
        SORT(yy); yy.erase(unique(all(yy)), yy.end());
        vector<vector<char> > have(n, vector<char>(n));
        vector<pii> b;
        rngi(i, n) {
            int x = a[i].first, y = a[i].second;
            x = lower_bound(all(xx), x) - xx.begin();
            y = lower_bound(all(yy), y) - yy.begin();
            b.push_back({ x,y });
            have[x][y] = 1;
        }
        vi cx(n), cy(n);
        rngi(i, n) cx[b[i].first]++;
        rngi(i, n) cy[b[i].second]++;

        rngi(i, n) rngi(j, n) {
            if (!ans)break;
            int x1 = b[i].first, y1 = b[i].second, x2 = b[j].first, y2 = b[j].second;
            if (x1 < x2 && y1 < y2) {
                int d = 4;
                if (have[x1][y2]) d -= 2;
                else if (cx[x1] > 1 || cy[y2] > 1) d--;

                if (have[x2][y1]) d -= 2;
                else if (cx[x2] > 1 || cy[y1] > 1) d--;
                ans = min(ans, d);
            }
        }
        rngi(i, n) a[i].second = -a[i].second;
    }
    cout << ans << '\n';
}
signed main()
{
    if (0) {
        freopen("1.in", "r", stdin);
        freopen("bad.out", "w", stdout);
    }
    srand(time(NULL));
    cin.tie(0);
    cout.tie(0);
    ios_base::sync_with_stdio(false);
    if (0) {
        cout << "50\n";
        rng(50) {
            int n = 1 + rand() % 10;
            cout << n << '\n';
            rng(n) {
                int x = rand() % 10, y = rand() % 10;
                cout << x << ' ' << y << '\n';
            }
        }
        return 0;
    }
    int t = 1; cin >> t;
    rng(t) solve();
}