#two elevators
def ab(n):
    if n<0:
        n*=-1
    return n
A,B,S=(int(i) for i in input().split())
da=ab(A-S)
db=ab(B-S)
if S==1:
    p=da+1
elif da<=db:
    p=da+S
elif A==0:
    p=db+S+1
elif A<=S:
    p=db+S
elif S-1<da:
    p=db+S-1+A
else:
    p=db+da+A
print(p)