using System;
using System.IO;
using System.Collections.Generic;
using System.Linq;
using System.Numerics;
using System.Runtime.CompilerServices;

namespace FertiLib.Contest.A
{
	static class Program
	{
		public static void Solve(Scanner cin)
		{
			int n = cin.ReadInt();
			var (x, y) = cin.ReadValueArray<int, int>(n);
			var xset = new Set<(int x, int i)>();
			var yset = new Set<(int y, int i)>();
			for (int i = 0; i < n; i++)
			{
				xset.Add((x[i], i));
				yset.Add((y[i], i));
			}
			var pq = new PriorityQueue<(long len, int index1, int index2)>();
			var uf = new UnionFind(n);
			for (int i = 1; i < n; i++)
			{
				pq.Enqueue((xset[i].x - xset[i - 1].x, xset[i].i, xset[i - 1].i));
				pq.Enqueue((yset[i].y - yset[i - 1].y, yset[i].i, yset[i - 1].i));
			}
			int con = 0;
			long ans = 0;
			while (con < n - 1)
			{
				var (nlen, nx, ny) = pq.Dequeue();
				if (!uf.IsSame(nx, ny))
				{
					uf.Unite(nx, ny);
					ans += nlen;
					con++;
				}
			}
			Console.WriteLine(ans);
		}

		public static void Main(string[] args)
		{
			var sw = new StreamWriter(Console.OpenStandardOutput()) { AutoFlush = false };
			Console.SetOut(sw);
			var cin = new Scanner();
			Solve(cin);
			Console.Out.Flush();
		}

		public static void YESNO(bool condition) => Console.WriteLine(condition ? "YES" : "NO");
		public static void YesNo(bool condition) => Console.WriteLine(condition ? "Yes" : "No");
		public static void yesno(bool condition) => Console.WriteLine(condition ? "yes" : "no");

		public static bool Chmax<T>(ref T a, T b) where T : IComparable<T>
		{
			if (a.CompareTo(b) >= 0) return false;
			a = b;
			return true;
		}
		public static bool Chmin<T>(ref T a, T b) where T : IComparable<T>
		{
			if (a.CompareTo(b) <= 0) return false;
			a = b;
			return true;
		}
	}

	public class UnionFind
	{
		public int Count { get; private set; }
		int[] parent;
		int[] depth;

		public UnionFind(int n)
		{
			parent = Enumerable.Range(0, n).ToArray();
			depth = Enumerable.Repeat(0, n).ToArray();
		}

		public void Unite(int x, int y)
		{
			x = Find(x);
			y = Find(y);
			if (x == y) return;
			if (depth[x] > depth[y])
			{
				parent[y] = x;
			}
			else
			{
				parent[x] = y;
				if (depth[x] == depth[y]) depth[x]++;
			}
		}

		public int Find(int x)
		{
			if (parent[x] == x) return x;
			else return parent[x] = Find(parent[x]);
		}

		public bool IsSame(int x, int y) => Find(x) == Find(y);
	}

	public class PriorityQueue<T> : IEnumerable<T>
	{
		private readonly List<T> heap;
		private readonly IComparer<T> comparer;

		public PriorityQueue(IComparer<T> comparer)
		{
			this.comparer = comparer;
			this.heap = new List<T>();
		}

		public PriorityQueue(Comparison<T> comparison) : this(Comparer<T>.Create(comparison)) { }

		public PriorityQueue() : this(Comparer<T>.Default) { }

		public void Enqueue(T item)
		{
			this.heap.Add(item);
			int index = this.Count - 1;
			while (index > 0)
			{
				var par = Parent(index);
				if (comparer.Compare(heap[index], heap[par]) >= 0) break;
				Swap(index, par);
				index = par;
			}
		}

		public T Dequeue()
		{
			var ret = this.Peek;
			var last = this.Count - 1;
			heap[0] = heap[last];
			heap.RemoveAt(last--);
			var index = 0;
			while (true)
			{
				var (r, l) = Child(index);
				int child;
				if (l <= last)
				{
					if (comparer.Compare(heap[l], heap[r]) < 0) child = l;
					else child = r;
				}
				else if (r <= last) child = r;
				else break;
				if (comparer.Compare(heap[index], heap[child]) <= 0) break;
				Swap(index, child);
				index = child;
			}
			return ret;
		}

		public T Peek => heap[0];

		public int Count => heap.Count;

		private void Swap(int a, int b)
		{
			var t = heap[a];
			heap[a] = heap[b];
			heap[b] = t;
		}

		private int Parent(int index) => (index - 1) / 2;

		private (int l, int r) Child(int index) => (2 * index + 1, 2 * index + 2);

		public IEnumerator<T> GetEnumerator()
		{
			var ret = new List<T>();
			while (this.Count > 0)
			{
				ret.Add(this.Dequeue());
			}

			for (int i = 0; i < ret.Count; i++)
			{
				this.Enqueue(ret[i]);
			}

			foreach (var e in ret)
			{
				yield return e;
			}
		}

		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() => GetEnumerator();
	}

	public class Set<T> : IEnumerable<T> where T : IComparable<T>
	{
		Node root;
		readonly IComparer<T> comparer;
		readonly Node nil;
		public bool IsMultiSet { get; set; }

		public Set() : this(Comparer<T>.Default) { }
		public Set(IComparer<T> comparer)
		{
			nil = new Node(default);
			root = nil;
			this.comparer = comparer;
		}
		public Set(Comparison<T> comparison) : this(Comparer<T>.Create(comparison)) { }

		public T this[int index]
		{
			get
			{
				if (index < 0 || root.Count < index) throw new ArgumentOutOfRangeException();
				return Find(root, index);
			}
		}

		public bool Add(T x) => Insert(ref root, x);
		public bool Remove(T x) => Erase(ref root, x);
		public void RemoveAt(int index)
		{
			if (index < 0 || Count < index) throw new ArgumentOutOfRangeException();
			EraseAt(ref root, index);
		}
		public bool Contains(T x) => this.Count == 0 ? false : EqualRange(x) > 0;
		public int LowerBound(T x) => BinarySearch(root, x, false);
		public int UpperBound(T x) => BinarySearch(root, x, true);
		public int EqualRange(T x) => UpperBound(x) - LowerBound(x);

		public void Clear() => root = nil;

		public T Min() => root.Min.Value;
		public T Max() => root.Max.Value;

		public T[] Items
		{
			get
			{
				var a = new T[root.Count];
				var k = 0;
				Walk(root, a, ref k);
				return a;
			}
		}
		public int Count => root.Count;
		public int Height => root.Height;

		public IEnumerator<T> GetEnumerator() { return Items.AsEnumerable().GetEnumerator(); }
		System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() => GetEnumerator();

		bool Insert(ref Node p, T x)
		{
			if (p.Count == 0)
			{
				p = new Node(x);
				p.Left = p.Right = nil;
				p.Update();
				return true;
			}
			bool ret;
			var t = comparer.Compare(p.Value, x);
			if (t > 0)
			{
				ret = Insert(ref p.Left, x);
			}
			else if (t < 0)
			{
				ret = Insert(ref p.Right, x);
			}
			else
			{
				if (IsMultiSet == true) ret = Insert(ref p.Left, x);
				else return false;
			}
			Balance(ref p);
			return ret;
		}

		bool Erase(ref Node p, T x)
		{
			if (p.Count == 0) return false;
			var t = comparer.Compare(p.Value, x);
			bool ret;
			if (t < 0) ret = Erase(ref p.Right, x);
			else if (t > 0) ret = Erase(ref p.Left, x);
			else
			{
				ret = true;
				if (p.Right.Count == 0) { p = p.Left; return true; }
				if (p.Left.Count == 0) { p = p.Right; return true; }

				p.Value = p.Left.Max.Value;
				Erase(ref p.Left, p.Left.Max.Value);
			}
			Balance(ref p);

			return ret;
		}

		void EraseAt(ref Node p, int index)
		{
			var count = p.Left.Count;
			if (index < count) EraseAt(ref p.Left, index);
			else if (index > count) EraseAt(ref p.Right, index - count - 1);
			else
			{
				if (p.Left.Count == 0) { p = p.Right; return; }
				if (p.Right.Count == 0) { p = p.Left; return; }

				p.Value = p.Left.Max.Value;
				EraseAt(ref p.Left, index - 1);
			}

			Balance(ref p);
		}

		void Walk(Node t, T[] a, ref int k)
		{
			if (t.Count == 0) return;
			Walk(t.Left, a, ref k);
			a[k++] = t.Value;
			Walk(t.Right, a, ref k);
		}

		void Balance(ref Node p)
		{
			var balance = p.Left.Height - p.Right.Height;
			if (balance < -1)
			{
				if (p.Right.Left.Height - p.Right.Right.Height > 0) RotateR(ref p.Right);
				RotateL(ref p);
			}
			else if (balance > 1)
			{
				if (p.Left.Left.Height - p.Left.Right.Height < 0) RotateL(ref p.Left);
				RotateR(ref p);
			}
			else p.Update();
		}

		T Find(Node p, int index)
		{
			if (index < p.Left.Count) return Find(p.Left, index);
			if (index > p.Left.Count) return Find(p.Right, index - p.Left.Count - 1);
			return p.Value;
		}

		void RotateL(ref Node p)
		{
			var r = p.Right;
			p.Right = r.Left;
			r.Left = p;
			p.Update();
			r.Update();
			p = r;
		}

		void RotateR(ref Node p)
		{
			var l = p.Left;
			p.Left = l.Right;
			l.Right = p;
			p.Update();
			l.Update();
			p = l;
		}

		int BinarySearch(Node p, T x, bool isUpperBound)
		{
			if (p.Count == 0) throw new NullReferenceException();

			var node = p;

			var ret = 0;

			while (p.Count != 0)
			{
				var cmp = p.Value.CompareTo(x);
				if (cmp > 0 || (!isUpperBound && cmp == 0))
				{
					p = p.Left;
				}
				else
				{
					ret += p.Left.Count + 1;
					p = p.Right;
				}
			}

			return ret;
		}

		public override string ToString()
		{
			return string.Join(", ", Items);
		}

		class Node
		{
			public Node Left, Right;
			public T Value { get; set; }

			public int Count { get; private set; }
			public int Height { get; private set; }

			public Node Min
			{
				get
				{
					if (Left.Count == 0) return this;
					else return Left.Min;
				}
			}

			public Node Max
			{
				get
				{
					if (Right.Count == 0) return this;
					else return Right.Max;
				}
			}

			public Node(T value) => Value = value;

			public void Update()
			{
				Count = Left.Count + Right.Count + 1;
				Height = Math.Max(Left.Height, Right.Height) + 1;
			}

			public override string ToString() => $"Count = {Count}, Value = {Value}";
		}
	}

	static class Extention
	{
		public static string Join<T>(this IEnumerable<T> x, string separator = "") => string.Join(separator, x);

		public static int UpperBound<T>(this IList<T> list, T value) => list.BinarySearch(value, true, 0, list.Count, Comparer<T>.Default);
		public static int LowerBound<T>(this IList<T> list, T value) => list.BinarySearch(value, false, 0, list.Count, Comparer<T>.Default);
		public static int BinarySearch<T>(this IList<T> list, T value, bool isUpperBound, int index, int length, Comparer<T> comparer)
		{
			var ng = index - 1;
			var ok = index + length;
			while (ok - ng > 1)
			{
				var mid = ng + (ok - ng) / 2;
				var res = comparer.Compare(list[mid], value);
				if (res < 0 || (isUpperBound && res == 0)) ng = mid;
				else ok = mid;
			}
			return ok;
		}
	}

	class Scanner
	{
		string[] s;
		int i;

		char[] separator = new char[] { ' ' };

		public Scanner()
		{
			s = new string[0];
			i = 0;
		}

		public string Read() => ReadString();

		public string ReadString()
		{
			if (i < s.Length) return s[i++];
			string st = Console.ReadLine();
			while (st == "") st = Console.ReadLine();
			s = st.Split(separator, StringSplitOptions.RemoveEmptyEntries);
			if (s.Length == 0) return ReadString();
			i = 0;
			return s[i++];
		}

		public string[] ReadStringArray(int N)
		{
			string[] Array = new string[N];
			for (int i = 0; i < N; i++)
			{
				Array[i] = ReadString();
			}
			return Array;
		}

		public int ReadInt()
		{
			return int.Parse(ReadString());
		}

		public int[] ReadIntArray(int N, int add = 0)
		{
			int[] Array = new int[N];
			for (int i = 0; i < N; i++)
			{
				Array[i] = ReadInt() + add;
			}
			return Array;
		}

		public long ReadLong()
		{
			return long.Parse(ReadString());
		}

		public long[] ReadLongArray(int N, long add = 0)
		{
			long[] Array = new long[N];
			for (int i = 0; i < N; i++)
			{
				Array[i] = ReadLong() + add;
			}
			return Array;
		}

		public double ReadDouble()
		{
			return double.Parse(ReadString());
		}

		public double[] ReadDoubleArray(int N, double add = 0)
		{
			double[] Array = new double[N];
			for (int i = 0; i < N; i++)
			{
				Array[i] = ReadDouble() + add;
			}
			return Array;
		}

		public T1 ReadValue<T1>() => (T1)Convert.ChangeType(ReadString(), typeof(T1));

		public (T1, T2) ReadValue<T1, T2>()
		{
			var inputs = ReadStringArray(2);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			return (v1, v2);
		}

		public (T1, T2, T3) ReadValue<T1, T2, T3>()
		{
			var inputs = ReadStringArray(3);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			var v3 = (T3)Convert.ChangeType(inputs[2], typeof(T3));
			return (v1, v2, v3);
		}

		public (T1, T2, T3, T4) ReadValue<T1, T2, T3, T4>()
		{
			var inputs = ReadStringArray(4);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			var v3 = (T3)Convert.ChangeType(inputs[2], typeof(T3));
			var v4 = (T4)Convert.ChangeType(inputs[3], typeof(T4));
			return (v1, v2, v3, v4);
		}

		public (T1, T2, T3, T4, T5) ReadValue<T1, T2, T3, T4, T5>()
		{
			var inputs = ReadStringArray(5);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			var v3 = (T3)Convert.ChangeType(inputs[2], typeof(T3));
			var v4 = (T4)Convert.ChangeType(inputs[3], typeof(T4));
			var v5 = (T5)Convert.ChangeType(inputs[4], typeof(T5));
			return (v1, v2, v3, v4, v5);
		}

		public (T1, T2, T3, T4, T5, T6) ReadValue<T1, T2, T3, T4, T5, T6>()
		{
			var inputs = ReadStringArray(6);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			var v3 = (T3)Convert.ChangeType(inputs[2], typeof(T3));
			var v4 = (T4)Convert.ChangeType(inputs[3], typeof(T4));
			var v5 = (T5)Convert.ChangeType(inputs[4], typeof(T5));
			var v6 = (T6)Convert.ChangeType(inputs[5], typeof(T6));
			return (v1, v2, v3, v4, v5, v6);
		}

		public (T1, T2, T3, T4, T5, T6, T7) ReadValue<T1, T2, T3, T4, T5, T6, T7>()
		{
			var inputs = ReadStringArray(7);
			var v1 = (T1)Convert.ChangeType(inputs[0], typeof(T1));
			var v2 = (T2)Convert.ChangeType(inputs[1], typeof(T2));
			var v3 = (T3)Convert.ChangeType(inputs[2], typeof(T3));
			var v4 = (T4)Convert.ChangeType(inputs[3], typeof(T4));
			var v5 = (T5)Convert.ChangeType(inputs[4], typeof(T5));
			var v6 = (T6)Convert.ChangeType(inputs[5], typeof(T6));
			var v7 = (T7)Convert.ChangeType(inputs[6], typeof(T7));
			return (v1, v2, v3, v4, v5, v6, v7);
		}

		public T1[] ReadValueArray<T1>(int N)
		{
			var v1 = new T1[N];
			for (int i = 0; i < N; i++)
			{
				v1[i] = ReadValue<T1>();
			}
			return v1;
		}

		public (T1[], T2[]) ReadValueArray<T1, T2>(int N)
		{
			var (v1, v2) = (new T1[N], new T2[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2) = ReadValue<T1, T2>();
				v1[i] = t1;
				v2[i] = t2;
			}
			return (v1, v2);
		}

		public (T1[], T2[], T3[]) ReadValueArray<T1, T2, T3>(int N)
		{
			var (v1, v2, v3) = (new T1[N], new T2[N], new T3[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2, t3) = ReadValue<T1, T2, T3>();
				v1[i] = t1;
				v2[i] = t2;
				v3[i] = t3;
			}
			return (v1, v2, v3);
		}

		public (T1[], T2[], T3[], T4[]) ReadValueArray<T1, T2, T3, T4>(int N)
		{
			var (v1, v2, v3, v4) = (new T1[N], new T2[N], new T3[N], new T4[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2, t3, t4) = ReadValue<T1, T2, T3, T4>();
				v1[i] = t1;
				v2[i] = t2;
				v3[i] = t3;
				v4[i] = t4;
			}
			return (v1, v2, v3, v4);
		}

		public (T1[], T2[], T3[], T4[], T5[]) ReadValueArray<T1, T2, T3, T4, T5>(int N)
		{
			var (v1, v2, v3, v4, v5) = (new T1[N], new T2[N], new T3[N], new T4[N], new T5[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2, t3, t4, t5) = ReadValue<T1, T2, T3, T4, T5>();
				v1[i] = t1;
				v2[i] = t2;
				v3[i] = t3;
				v4[i] = t4;
				v5[i] = t5;
			}
			return (v1, v2, v3, v4, v5);
		}

		public (T1[], T2[], T3[], T4[], T5[], T6[]) ReadValueArray<T1, T2, T3, T4, T5, T6>(int N)
		{
			var (v1, v2, v3, v4, v5, v6) = (new T1[N], new T2[N], new T3[N], new T4[N], new T5[N], new T6[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2, t3, t4, t5, t6) = ReadValue<T1, T2, T3, T4, T5, T6>();
				v1[i] = t1;
				v2[i] = t2;
				v3[i] = t3;
				v4[i] = t4;
				v5[i] = t5;
				v6[i] = t6;
			}
			return (v1, v2, v3, v4, v5, v6);
		}

		public (T1[], T2[], T3[], T4[], T5[], T6[], T7[]) ReadValueArray<T1, T2, T3, T4, T5, T6, T7>(int N)
		{
			var (v1, v2, v3, v4, v5, v6, v7) = (new T1[N], new T2[N], new T3[N], new T4[N], new T5[N], new T6[N], new T7[N]);
			for (int i = 0; i < N; i++)
			{
				var (t1, t2, t3, t4, t5, t6, t7) = ReadValue<T1, T2, T3, T4, T5, T6, T7>();
				v1[i] = t1;
				v2[i] = t2;
				v3[i] = t3;
				v4[i] = t4;
				v5[i] = t5;
				v6[i] = t6;
				v7[i] = t7;
			}
			return (v1, v2, v3, v4, v5, v6, v7);
		}
	}
}


Measured memory_bytes: 50808