import sys

class Point:
	def __init__(self, x, y):
		self.x = x
		self.y = y

class Volcanoes:
	def sortdata(self):
		self.input.pop(0)
		self.input.pop(len(self.input)-1)
		self.vol = []
		for s in self.input:
			self.vol.append(s.split(" "))		
	def solver(self):
		self.vol.sort(key = lambda pair:pair[1])
		self.vol.sort(key = lambda pair: pair[0])
		result = 0
		tmplist = []
		currx = 0
		i = 0
		while(i < len(self.vol)-1):
			currx = int(self.vol[i][0])
			#if currx != self.vol[i+1][0]:
			x = int(self.vol[i+1][0]) - int(self.vol[i][0])
			y = int(self.vol[i+1][1]) - int(self.vol[i][1])
			result += abs(x) + abs(y)
			#else:
				#while currx == self.vol[i][0]:
					#tmplist.append(self.vol[i])			
					#i+=1
			i += 1
				
		print(result)
	
	def __init__(self):
		self.input = sys.stdin.read()
		self.input = self.input.split('\n')
		self.sortdata()
		self.solver()	

v = Volcanoes()