a,b,c = map(int,input().split())
ans = 0
if a <= b <= c:
    print(0)
    exit()
if a ==c:
    print(abs(a-b)+1)
    exit()
if a > c:
    a,c = c,a

if b < a:
    ans = a-b+1

else:
    ans = b-c+1


ans = min(ans,c-a)
print(ans)