Mixing Milk

def pour(amount1,amount2,capacity):
    # Returns the amount of milk left in the first bucket
    # after pouring as much of it as possible into the
    # second bucket.
    # amount1: amount of milk in the first bucket
    # amount2: amount of milk in the second bucket
    # capacity: capacity of the second bucket
    left = capacity-amount2 # how much more milk can the second bucket hold?
    shift = min(left,amount1) # how much milk is poured?
    return amount1-shift,amount2+shift

def pourCycle(a1,a2,a3,cap1,cap2,cap3):
    # pour a->b, b->c and c->a.
    # a1, a2, a3: amount of milk in each bucket.
    # cap1, cap2, cap3: capacity of each bucket.
    a1,a2 = pour(a1,a2,cap2)
    a2,a3 = pour(a2,a3,cap3)
    a3,a1 = pour(a3,a1,cap1)
    return a1,a2,a3

def main():
    # read input
    # a_i = amount of bucket i
    # c_i = capacity of bucket i
    with open('mixmilk.in','r') as fIn:
        c1,a1 = map(int,fIn.readline().split())
        c2,a2 = map(int,fIn.readline().split())
        c3,a3 = map(int,fIn.readline().split())
    for _ in range(33): # 33 pour operations = 99 pours
        a1,a2,a3 = pourCycle(a1,a2,a3,c1,c2,c3)
    a1,a2 = pour(a1,a2,c2) # 100th pour
    print(a1,a2,a3)
    with open('mixmilk.out','w') as fOut:
        fOut.write('%d\n%d\n%d\n'%(a1,a2,a3))

main()