//    _____                   _                       _
//   / ____|                 | |                     (_)
//  | (___   ___  _ __     __| | ___ _ __    ______ _ _
//   \___ \ / _ \| '_ \   / _` |/ _ \ '_ \  |_  / _` | |
//   ____) | (_) | | | | | (_| |  __/ |_) |  / / (_| | |
//  |_____/ \___/|_| |_|  \__,_|\___| .__/  /___\__,_|_|
//                                  | |
//                                  |_|

#include <bits/stdc++.h>
#define nmax 100005
#define oo 10000000007
#define mod 1000000007
#define reset(x) memset(x, 0, sizeof x)
#define F first
#define S second
#define sonin cin
#define sonout cout
#define PB(x) push_back(x)
#define debug(x) cout << "Loli -> " << #x << " : " << x << "\n"
#define filename ""
#define fileNX freopen(filename".inp", "r", stdin); freopen(filename".out", "w", stdout);
#define fileN freopen(filename".inp", "r", stdin);
#define fileX freopen(filename".out", "w", stdout);
#define toiuuhoa ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#define SZ(a) (int) a.size()
#define FOU(x,a,b) for (lli x=a;x<=b;x++)
#define FOD(x,a,b) for (lli x=a;x>=b;x--)
#define FOA(a,b) for(auto &a:b)
#define ALLvec(a) a.begin(),a.end()
#define REU(x,a,b) for (lli x=a;x<b;x++)
#define RED(x,a,b) for (lli x=a;x>b;x--)
#define AutoCinAry(a,b,x) for(int a = 1; a<=b; a++) cin >> x[i];
#define dembit1(x) __builtin_popcount(x)
#define bit(x,i) (x>>(i-1)&1ll)
#define on(x,i) (x|(1ll<<(i-1)))
#define off(x,i) (x&~(1ll<<(i-1)))
#define EL cout << "\n";
#define EX exit(0);
#define Ary(x, i, j, a) x[(i - 1) * a + j]
#define epsinon 1e-8
using namespace std;
const int base = 1000000000; const int base_digits = 9;
struct bigint { vector<int> a; int sign; bigint() : sign(1) { } bigint(long long v) { *this = v; } bigint(const string &s) { read(s); } void operator=(const bigint &v) { sign = v.sign; a = v.a; } void operator=(long long v) { sign = 1; if (v < 0) sign = -1, v = -v; for (; v > 0; v = v / base) a.push_back(v % base); } bigint operator+(const bigint &v) const { if (sign == v.sign) { bigint res = v; for (int i = 0, carry = 0; i < (int) max(a.size(), v.a.size()) || carry; ++i) { if (i == (int) res.a.size()) res.a.push_back(0); res.a[i] += carry + (i < (int) a.size() ? a[i] : 0); carry = res.a[i] >= base; if (carry) res.a[i] -= base; } return res; } return *this - (-v); } bigint operator-(const bigint &v) const { if (sign == v.sign) { if (abs() >= v.abs()) { bigint res = *this; for (int i = 0, carry = 0; i < (int) v.a.size() || carry; ++i) { res.a[i] -= carry + (i < (int) v.a.size() ? v.a[i] : 0); carry = res.a[i] < 0; if (carry) res.a[i] += base; } res.trim(); return res; } return -(v - *this); } return *this + (-v); } void operator*=(int v) { if (v < 0) sign = -sign, v = -v; for (int i = 0, carry = 0; i < (int) a.size() || carry; ++i) { if (i == (int) a.size()) a.push_back(0); long long cur = a[i] * (long long) v + carry; carry = (int) (cur / base); a[i] = (int) (cur % base);asm("divl %%ecx" : "=a"(carry), "=d"(a[i]) : "A"(cur), "c"(base)); } trim(); } bigint operator*(int v) const { bigint res = *this; res *= v; return res; } friend pair<bigint, bigint> divmod(const bigint &a1, const bigint &b1) { int norm = base / (b1.a.back() + 1); bigint a = a1.abs() * norm; bigint b = b1.abs() * norm; bigint q, r; q.a.resize(a.a.size()); for (int i = a.a.size() - 1; i >= 0; i--) { r *= base; r += a.a[i]; int s1 = r.a.size() <= b.a.size() ? 0 : r.a[b.a.size()]; int s2 = r.a.size() <= b.a.size() - 1 ? 0 : r.a[b.a.size() - 1]; int d = ((long long) base * s1 + s2) / b.a.back(); r -= b * d; while (r < 0) r += b, --d; q.a[i] = d; } q.sign = a1.sign * b1.sign; r.sign = a1.sign; q.trim(); r.trim(); return make_pair(q, r / norm); } bigint operator/(const bigint &v) const { return divmod(*this, v).first; } bigint operator%(const bigint &v) const { return divmod(*this, v).second; } void operator/=(int v) { if (v < 0) sign = -sign, v = -v; for (int i = (int) a.size() - 1, rem = 0; i >= 0; --i) { long long cur = a[i] + rem * (long long) base; a[i] = (int) (cur / v); rem = (int) (cur % v); } trim(); } bigint operator/(int v) const { bigint res = *this; res /= v; return res; } int operator%(int v) const { if (v < 0) v = -v; int m = 0; for (int i = a.size() - 1; i >= 0; --i) m = (a[i] + m * (long long) base) % v; return m * sign; } void operator+=(const bigint &v) { *this = *this + v; } void operator-=(const bigint &v) { *this = *this - v; } void operator*=(const bigint &v) { *this = *this * v; } void operator/=(const bigint &v) { *this = *this / v; } bool operator<(const bigint &v) const { if (sign != v.sign) return sign < v.sign; if (a.size() != v.a.size()) return a.size() * sign < v.a.size() * v.sign; for (int i = a.size() - 1; i >= 0; i--) if (a[i] != v.a[i]) return a[i] * sign < v.a[i] * sign; return false; } bool operator>(const bigint &v) const { return v < *this; } bool operator<=(const bigint &v) const { return !(v < *this); } bool operator>=(const bigint &v) const { return !(*this < v); } bool operator==(const bigint &v) const { return !(*this < v) && !(v < *this); } bool operator!=(const bigint &v) const { return *this < v || v < *this; } void trim() { while (!a.empty() && !a.back()) a.pop_back(); if (a.empty()) sign = 1; } bool isZero() const { return a.empty() || (a.size() == 1 && !a[0]); } bigint operator-() const { bigint res = *this; res.sign = -sign; return res; } bigint abs() const { bigint res = *this; res.sign *= res.sign; return res; } long long longValue() const { long long res = 0; for (int i = a.size() - 1; i >= 0; i--) res = res * base + a[i]; return res * sign; } friend bigint gcd(const bigint &a, const bigint &b) { return b.isZero() ? a : gcd(b, a % b); } friend bigint lcm(const bigint &a, const bigint &b) { return a / gcd(a, b) * b; } void read(const string &s) { sign = 1; a.clear(); int pos = 0; while (pos < (int) s.size() && (s[pos] == '-' || s[pos] == '+')) { if (s[pos] == '-') sign = -sign; ++pos; } for (int i = s.size() - 1; i >= pos; i -= base_digits) { int x = 0; for (int j = max(pos, i - base_digits + 1); j <= i; j++) x = x * 10 + s[j] - '0'; a.push_back(x); } trim(); } friend istream& operator>>(istream &stream, bigint &v) { string s; stream >> s; v.read(s); return stream; } friend ostream& operator<<(ostream &stream, const bigint &v) { if (v.sign == -1) stream << '-'; stream << (v.a.empty() ? 0 : v.a.back()); for (int i = (int) v.a.size() - 2; i >= 0; --i) stream << setw(base_digits) << setfill('0') << v.a[i]; return stream; } static vector<int> convert_base(const vector<int> &a, int old_digits, int new_digits) { vector<long long> p(max(old_digits, new_digits) + 1); p[0] = 1; for (int i = 1; i < (int) p.size(); i++) p[i] = p[i - 1] * 10; vector<int> res; long long cur = 0; int cur_digits = 0; for (int i = 0; i < (int) a.size(); i++) { cur += a[i] * p[cur_digits]; cur_digits += old_digits; while (cur_digits >= new_digits) { res.push_back(int(cur % p[new_digits])); cur /= p[new_digits]; cur_digits -= new_digits; } } res.push_back((int) cur); while (!res.empty() && !res.back()) res.pop_back(); return res; } typedef vector<long long> vll; static vll karatsubaMultiply(const vll &a, const vll &b) { int n = a.size(); vll res(n + n); if (n <= 32) { for (int i = 0; i < n; i++) for (int j = 0; j < n; j++) res[i + j] += a[i] * b[j]; return res; } int k = n >> 1; vll a1(a.begin(), a.begin() + k); vll a2(a.begin() + k, a.end()); vll b1(b.begin(), b.begin() + k); vll b2(b.begin() + k, b.end()); vll a1b1 = karatsubaMultiply(a1, b1); vll a2b2 = karatsubaMultiply(a2, b2); for (int i = 0; i < k; i++) a2[i] += a1[i]; for (int i = 0; i < k; i++) b2[i] += b1[i]; vll r = karatsubaMultiply(a2, b2); for (int i = 0; i < (int) a1b1.size(); i++) r[i] -= a1b1[i]; for (int i = 0; i < (int) a2b2.size(); i++) r[i] -= a2b2[i]; for (int i = 0; i < (int) r.size(); i++) res[i + k] += r[i]; for (int i = 0; i < (int) a1b1.size(); i++) res[i] += a1b1[i]; for (int i = 0; i < (int) a2b2.size(); i++) res[i + n] += a2b2[i]; return res; } bigint operator*(const bigint &v) const { vector<int> a6 = convert_base(this->a, base_digits, 6); vector<int> b6 = convert_base(v.a, base_digits, 6); vll a(a6.begin(), a6.end()); vll b(b6.begin(), b6.end()); while (a.size() < b.size()) a.push_back(0); while (b.size() < a.size()) b.push_back(0); while (a.size() & (a.size() - 1)) a.push_back(0), b.push_back(0); vll c = karatsubaMultiply(a, b); bigint res; res.sign = sign * v.sign; for (int i = 0, carry = 0; i < (int) c.size(); i++) { long long cur = c[i] + carry; res.a.push_back((int) (cur % 1000000)); carry = (int) (cur / 1000000); } res.a = convert_base(res.a, 6, base_digits); res.trim(); return res; } };

typedef long long lli;
typedef long double ldo;
typedef double dou;
typedef vector<lli> vi;
typedef vector<vi> vvi;
typedef pair<lli, lli> pii;
typedef vector<pii> vpi;

lli n;
int d[nmax], outside[nmax], Sum;
struct xyz{
    int x,y,z;
};
xyz p[nmax];
vpi e[nmax];

//Thông số cạnh lưu vào mảng cây khung
struct ad3{
int first, second, u;
};
//Thông số mỗi đỉnh
struct ad{
int v, w;
};
//Thông số cạnh lưu vào mảng cây khung
struct ad2{
int u, v, w;
};

//Function ưu tiên lấy giá trị nhỏ của trọng số W
struct cmpc{
bool operator()(ad3 a, ad3 b){
    return a.second > b.second;
}
};

void prim() {
    int ff = 1;
    //Ưu tiên
    priority_queue<ad3, vector<ad3>, cmpc> qu;
    //Tự do cho các đỉnh
    memset(outside, 1, sizeof outside);
    //Set các nhãn bằng vô cực
    for (int i=1; i<=n; i++) d[i]=oo;
    //Thêm vào hàng đợi ưu tiên đỉnh u với trọng số là 0 và nhãn dán của u là 0
    qu.push({ff, 0, 1}); d[ff]=0;
    //U nằm trong cây khung
    outside[ff]=false;
    while (!qu.empty()) {
        // Lấy phần tử ưu tiên nhất
        ad3 pp=qu.top();
        qu.pop();
        //Lấy dữ liệu
        int u = pp.first;
        int du = pp.second;
        if (du!=d[u]) continue;
        //Tổng
        Sum+=d[u];
        d[u]=0;
        //Xét các đỉnh kề của U
        for (int i=0; i < e[u].size(); i++){
            if (d[e[u][i].F] > e[u][i].S && outside[e[u][i].F]) {
                //đặt d của v là w của cạnh (u,v)
                d[e[u][i].F] = e[u][i].S;
                // Thêm đỉnh v và nhãn dán d của v vào hàng đợi ưu tiên
                qu.push({e[u][i].F, d[e[u][i].F], u});
            }
        }
        outside[u] = false;
    }
}

bool cmp1(xyz a, xyz b){
    return a.x < b.x;
}
bool cmp2(xyz a, xyz b){
    return a.y < b.y;
}

main(){
    //fileNX
    toiuuhoa
    sonin >> n;

    FOU(i,1,n){
        sonin >> p[i].x >> p[i].y;
        p[i].z = i;
    }

    sort(p+1, p+n+1, cmp1);
    FOU(i,2,n){
        e[p[i].z].push_back({p[i-1].z, abs(p[i].x - p[i-1].x)});
        e[p[i-1].z].push_back({p[i].z, abs(p[i].x - p[i-1].x)});
    }
    sort(p+1, p+n+1, cmp2);
    FOU(i,2,n){
        e[p[i].z].push_back({p[i-1].z, abs(p[i].y - p[i-1].y)});
        e[p[i-1].z].push_back({p[i].z, abs(p[i].y - p[i-1].y)});
    }

    prim();

    sonout << Sum;

}


Measured memory_bytes: 15224