# ユニオンファインド

class UnionFind():

    def __init__(self, n):

        self.n = n

        self.parents = [-1] * n



    def find(self, x):

        if self.parents[x] < 0:

            return x

        else:

            self.parents[x] = self.find(self.parents[x])

            return self.parents[x]



    def union(self, x, y):

        x = self.find(x)

        y = self.find(y)



        if x == y:

            return



        if self.parents[x] > self.parents[y]:

            x, y = y, x



        self.parents[x] += self.parents[y]

        self.parents[y] = x



    def size(self, x):

        return -self.parents[self.find(x)]



    def same(self, x, y):

        return self.find(x) == self.find(y)



    def members(self, x):

        root = self.find(x)

        return [i for i in range(self.n) if self.find(i) == root]



    def roots(self):

        return [i for i, x in enumerate(self.parents) if x < 0]



    def group_count(self):

        return len(self.roots())



    def all_group_members(self):

        return {r: self.members(r) for r in self.roots()}



    def __str__(self):

        return '\n'.join('{}: {}'.format(r, self.members(r)) for r in self.roots())



n=int(eval(input()))

a= [list(map(int, input().split())) for i in range(n)]

b=[]

a.sort()

# aの各点に通し番号を振る

for i in range(n):

    a[i].append(i)



# 繋ぐ点の候補は上下左右の４つ

# 左右に繋ぐ辺を追加

for i in range(n-1):

    b.append([a[i][2], a[i + 1][2], a[i + 1][0] - a[i][0]])



a.sort(key=lambda x:x[1])

# 上下に繋ぐ辺を追加

for i in range(n-1):

    b.append([a[i][2], a[i + 1][2], a[i + 1][1] - a[i][1]])



b.sort(key=lambda x:x[2])



uf=UnionFind(n)

ans=0

cnt=0

# クラスカル法

for x,y,z in b:

    if not uf.same(x,y):

        uf.union(x,y)

        cnt+=1

        ans+=z

        if cnt==n-1:

            break

print(ans)

import sys

input = sys.stdin.readline



# ユニオンファインド

class UnionFind():

    def __init__(self, n):

        self.n = n

        self.parents = [-1] * n



    def find(self, x):

        if self.parents[x] < 0:

            return x

        else:

            self.parents[x] = self.find(self.parents[x])

            return self.parents[x]



    def union(self, x, y):

        x = self.find(x)

        y = self.find(y)



        if x == y:

            return



        if self.parents[x] > self.parents[y]:

            x, y = y, x



        self.parents[x] += self.parents[y]

        self.parents[y] = x







    def same(self, x, y):

        return self.find(x) == self.find(y)





n=int(eval(input()))

a= [list(map(int, input().split())) for i in range(n)]

b=[]

a.sort()

# aの各点に通し番号を振る

for i in range(n):

    a[i].append(i)



# 繋ぐ点の候補は上下左右の４つ

# 左右に繋ぐ辺を追加

for i in range(n-1):

    b.append([a[i][2], a[i + 1][2], a[i + 1][0] - a[i][0]])



a.sort(key=lambda x:x[1])

# 上下に繋ぐ辺を追加

for i in range(n-1):

    b.append([a[i][2], a[i + 1][2], a[i + 1][1] - a[i][1]])



b.sort(key=lambda x:x[2])



uf=UnionFind(n)

ans=0

cnt=0

# クラスカル法

for x,y,z in b:

    if not uf.same(x,y):

        uf.union(x,y)

        cnt+=1

        ans+=z

        if cnt==n-1:

            break

print(ans)

# ユニオンファインド
class UnionFind:
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        if self.parents[x] > self.parents[y]:
            x, y = y, x
        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def size(self, x):
        return -self.parents[self.find(x)]

    def same(self, x, y):
        return self.find(x) == self.find(y)

    def members(self, x):
        root = self.find(x)
        return [i for i in range(self.n) if self.find(i) == root]

    def roots(self):
        return [i for i, x in enumerate(self.parents) if x < 0]

    def group_count(self):
        return len(self.roots())

    def all_group_members(self):
        return {r: self.members(r) for r in self.roots()}

    def __str__(self):
        return "\n".join("{}: {}".format(r, self.members(r)) for r in self.roots())


n = int(eval(input()))
a = [list(map(int, input().split())) for i in range(n)]
b = []
a.sort()
# aの各点に通し番号を振る
for i in range(n):
    a[i].append(i)
# 繋ぐ点の候補は上下左右の４つ
# 左右に繋ぐ辺を追加
for i in range(n - 1):
    b.append([a[i][2], a[i + 1][2], a[i + 1][0] - a[i][0]])
a.sort(key=lambda x: x[1])
# 上下に繋ぐ辺を追加
for i in range(n - 1):
    b.append([a[i][2], a[i + 1][2], a[i + 1][1] - a[i][1]])
b.sort(key=lambda x: x[2])
uf = UnionFind(n)
ans = 0
cnt = 0
# クラスカル法
for x, y, z in b:
    if not uf.same(x, y):
        uf.union(x, y)
        cnt += 1
        ans += z
        if cnt == n - 1:
            break
print(ans)

import sys

input = sys.stdin.readline
# ユニオンファインド
class UnionFind:
    def __init__(self, n):
        self.n = n
        self.parents = [-1] * n

    def find(self, x):
        if self.parents[x] < 0:
            return x
        else:
            self.parents[x] = self.find(self.parents[x])
            return self.parents[x]

    def union(self, x, y):
        x = self.find(x)
        y = self.find(y)
        if x == y:
            return
        if self.parents[x] > self.parents[y]:
            x, y = y, x
        self.parents[x] += self.parents[y]
        self.parents[y] = x

    def same(self, x, y):
        return self.find(x) == self.find(y)


n = int(eval(input()))
a = [list(map(int, input().split())) for i in range(n)]
b = []
a.sort()
# aの各点に通し番号を振る
for i in range(n):
    a[i].append(i)
# 繋ぐ点の候補は上下左右の４つ
# 左右に繋ぐ辺を追加
for i in range(n - 1):
    b.append([a[i][2], a[i + 1][2], a[i + 1][0] - a[i][0]])
a.sort(key=lambda x: x[1])
# 上下に繋ぐ辺を追加
for i in range(n - 1):
    b.append([a[i][2], a[i + 1][2], a[i + 1][1] - a[i][1]])
b.sort(key=lambda x: x[2])
uf = UnionFind(n)
ans = 0
cnt = 0
# クラスカル法
for x, y, z in b:
    if not uf.same(x, y):
        uf.union(x, y)
        cnt += 1
        ans += z
        if cnt == n - 1:
            break
print(ans)

+import sys + +input = sys.stdin.readline -    def size(self, x): -        return -self.parents[self.find(x)] - - -    def members(self, x): -        root = self.find(x) -        return [i for i in range(self.n) if self.find(i) == root] - -    def roots(self): -        return [i for i, x in enumerate(self.parents) if x < 0] - -    def group_count(self): -        return len(self.roots()) - -    def all_group_members(self): -        return {r: self.members(r) for r in self.roots()} - -    def __str__(self): -        return "\n".join("{}: {}".format(r, self.members(r)) for r in self.roots())