import sys, re
# ranges are inclusive from both ends

def range_intersect(a, b):
	return a[0] <= b[0] <= a[1] or a[0] <= b[1] <= a[1] or b[0] <= a[0] <= b[1] or b[0] <= a[1] <= b[1]

class RangeSet:
	def __init__(self):
		self.rs = []
	def add(self, a, b):
		for i in range(len(self.rs)):
			r = self.rs[i]
			if range_intersect(r, (a, b)):
				a = min(a, r[0])
				b = max(b, r[1])
				self.rs[i] = None
		self.rs = [r for r in self.rs if r]
		self.rs.append((a, b))
	def size(self):
		s = 0
		for r in self.rs:
			s += r[1] - r[0] + 1
		return s

data = []
for line in sys.stdin:
	data.append([int(n) for n in re.findall('\d+', line)])

manhattan = [abs(a[0] - a[2]) + abs(a[1] - a[3]) for a in data]

def partOne(y):
	r = RangeSet()
	for l, m in zip(data, manhattan):
		w = m - abs(l[1] - y)
		if w < 0: continue
		#print(l, w, l[0] - w, l[0] + w)
		r.add(l[0] - w, l[0] + w)
	beacons = set([(a[2], a[3]) for a in data if a[3] == y])
	return r.size() - len(beacons)

print(partOne(2000000))