def kado(A,B,C):
    if A!=B and A!=C and B!=C and (max(A,B,C)==B or min(A,B,C)==B):
        return 1
    return 0

A,B,C=map(int,input().split())
S=sorted([A,B,C])
CAN=[S[2]-S[1],S[2]-S[0],S[1]-S[0],0]
CAN2=[]
for i in CAN:
    for j in range(i-3,i+2):
        if j>=0:
            CAN2.append(j)

from itertools import product

P=list(product(CAN2,repeat=3))
ANS=1<<31

for x,y,z in P:
    if kado(A-x,B-y,C-z)==0:
        ANS=min(ANS,x+y+z)

print(ANS)