beacons = []
sensors = []
lineY = 2000000
vectors = []

def loop():
    for j in range(len(vectors)):
        for i in range(len(vectors)):
            if j != i:
                if vectors[j][0] in range (vectors[i][0], vectors[i][1]) or vectors[i][0] in range (vectors[j][0], vectors[j][1]):
                    tempSt = min(vectors[j][0],vectors[i][0])
                    tempEn = max(vectors[j][1],vectors[i][1])
                    vectors.append((tempSt, tempEn))
                    vectors.pop(max(i, j))
                    vectors.pop(min(i, j))
                    return False
    return True

with open('input15.txt','r') as f:
    inp = f.read().splitlines(keepends=False)

for line in inp:
    tempA, tempB = line.split(': closest beacon is at x=')
    tempA = tempA.replace('Sensor at x=', '')
    tempA = tempA.split(', y=')
    sensors.append(tuple(map(int, tempA)))
    tempB = tempB.split(', y=')
    beacons.append(tuple(map(int, tempB)))



for i in range(len(sensors)):
    print('checking sensor', i, 'out of', len(sensors) - 1)
    (sensX, sensY) = sensors[i]
    (beacX, beacY) = beacons[i]
    distance = (max(sensX, beacX) - min(sensX, beacX)) + (max(sensY, beacY) - min(sensY, beacY))
    if sensY <= lineY and (sensY + distance) >= lineY:
        modifier = distance - (lineY - sensY)
        vectors.append((sensX - modifier, sensX + modifier))
    elif sensY >= lineY and (sensY - distance) <= lineY: 
        modifier = distance - (sensY - lineY)
        vectors.append((sensX - modifier, sensX + modifier))

done = False
tempA = []

while not done:
    done = loop()

vectors = sorted(vectors)

CoveredPoints = vectors[-1][1] - vectors[0][0] + 1
for i in range(len(vectors) - 1):
    if vectors[i + 1][0] != vectors[i][1]:
        CoveredPoints -= (vectors[i + 1][0] - vectors[i][1] - 1)
for beacon in beacons:
    if beacon[1] == lineY and beacon not in tempA:
        tempA.append(beacon)
        CoveredPoints -= 1

print(CoveredPoints)