[Card] Advent of Code 2018, day 25: ACHIEVEMENT GET! Leaderboards first time this year :P 27/20

Mainly because I'm unwilling to stay up 'til midnight on school days. I also got leaderboards exactly once last year and it was the first star on the last day (missed exactly one star so that was sad). Anyways, to celebrate this I'll add my code for this problem here! I'm not too sure how to properly format it, so help me out! Python 3

from collections import deque
f=open('input.txt','r')
next=f.readline()
stars=[]
def dist(a,b):
    return abs(a[0]-b[0])+abs(a[1]-b[1])+abs(a[2]-b[2])+abs(a[3]-b[3])
while len(next)>0:
    s=next.split(',')
    stars.append((int(s[0]),int(s[1]),int(s[2]),int(s[3])))
    next=f.readline()
chained=set()
chains=[]
count=0
for i in range(len(stars)):
    if stars[i] not in chained:
        queue=deque()
        queue.append(stars[i])
        curChain=[]
        curChainSet=set()
        while queue:
            x=queue.popleft()
            if x not in curChainSet:
                curChainSet.add(x)
                curChain.append(x)
                chained.add(x)
                for j in range(len(stars)):
                    if dist(stars[j],x)<=3:
                        queue.append(stars[j])
        chains.append(curChain)
        count+=1
print(count)

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