#!/usr/bin/python3
import fileinput
import re

targety = 2000000

sensors = []
beacons = set()
beacons_on_target_y = 0

r = r'Sensor at x=(-?\d+), y=(-?\d+).*beacon is at x=(-?\d+), y=(-?\d+)'
for line in fileinput.input():
	result = re.search(r, line)
	sx, sy, bx, by = list(map(int, result.groups()))
	dist = abs(bx-sx) + abs(by-sy)
	sensors.append((sx,sy,dist))
	beacons.add((bx,by))

for b in beacons:
	if b[1] == targety:
		beacons_on_target_y += 1

# Project each sensor's coverage diamond onto the target row.
# Number of cells covered is either 0, or an odd number (1, 3, 5, ...).
# 
# .................#.....
# ................###.... <= target row
# ........#......#####...
# ..#....###....#######..
# .#S#..##S##..####S####.
# ..#....###....#######..
# ........#......#####...
# ................###....
# .................#.....
# 
# With the sensor 3 units away vertically, range 1 or 2 provides no coverage.
# Range 3 (= dY) provides 1 unit of coverage at sensor's X.
# Range dY+1 provides 3 units of coverage, SX-1 to SX+1.
# Range dY+n provides 2n+1 coverage, from SX-n to SX+n.

coverage = []
for s in sensors:
	sx, sy, srange = s
	dist = abs(sy - targety)
	if dist > srange:
		continue
	coverage.append((sx-(srange-dist),sx+(srange-dist)))

# print(coverage)

# Remove redundant coverage elements.
# Use stuff from day 4 part 1.
redundant = [False] * len(coverage)
for i in range(0, len(coverage)-1):
	for j in range(i+1, len(coverage)):
		if i == j:
			continue
		a, b = coverage[i]
		c, d = coverage[j]
		considered = j
		if (a > c) or (a == c and d > b):
			a, b, c, d = c, d, a, b
			considered = i
		if a <= c and b >= d:
			redundant[considered] = True

# print(redundant)
newlist = []
for i in range(0, len(coverage)):
	if not redundant[i]:
		newlist.append(coverage[i])
coverage = newlist

# print(coverage)

# Now see how many tiles of the target Y are covered.
# Start by finding the lowest and highest covered tiles.
xmin, xmax = coverage[0]
for c in coverage:
	if c[0] < xmin:
		xmin = c[0]
	if c[1] > xmax:
		xmax = c[1]

total = 0
for x in range(xmin, xmax+1):
	for c in coverage:
		if x >= c[0] and x <= c[1]:
			total += 1
			break

print(total - beacons_on_target_y)