#!/usr/bin/env python3
import re

lines = (x.strip() for x in open("input.txt"))
lines = [tuple(map(int, re.search(r"(-?\d+).+?(-?\d+).+?(-?\d+).+?(-?\d+)", line).groups())) for line in lines]

for target in range(0, 4000000): #3186981
    if target % 40000 == 0:
        print(target/4000000)
    intervals = []
    known_targets = set()

    for line in lines:
        x, y, a, b = line
        dist = abs(x-a) + abs(y-b)
        width = dist-abs(y-target)
        if width >= 0:
            intervals.append((x-width, x+width))
        if b == target:
            known_targets.add(a)
        if y == target:
            known_targets.add(x)


    intervals.sort(key=lambda x: x[0])
    merged = [intervals[0]]
    for i in intervals[1:]:
        if merged[-1][1] >= i[0]:
            merged[-1] = (merged[-1][0], max(merged[-1][1], i[1]))
        else:
            merged.append(i)

    if len(merged) > 1:
        print(target, merged, (merged[0][1]+1)*4000000+target)
        break