dirstack = [] # Stack of directories we are currently at
directories = {} # Maps paths to total filesums

TOTAL = 70000000
REQUIRED = 30000000

def addsize(size):
    for (i, dir) in enumerate(dirstack):
        path = "/".join(dirstack[:i+1])
        if not path in directories:
            directories[path] = 0
        directories[path] += size

with open("input.txt", "r") as f:
    for line in f.readlines():
        line = line.strip()
        if line[0] == '$' and line[2] == 'c':
            folder = line.split("$ cd ")[1]
            if folder == '..':
                dirstack.pop()
            else:
                dirstack.append(folder)
        else:
            indicator = line.split(" ")[0]
            try:
                size = int(indicator)
                addsize(size)
            except:
                pass

FREE = TOTAL - directories["/"]
NEEDED = REQUIRED-FREE

print(f"We have {FREE} space, but need {REQUIRED} so we need {NEEDED}")

candidates = sorted(directories, key=directories.get)
for candidate in candidates:
    if directories[candidate] > NEEDED:
        print(directories[candidate])
        break