A, B, C = map(int, input().split())

ans1 = 0
ans2 = min(abs(A - C), abs(A - B), abs(B - C))

if A == C:
    C -= 1
    ans1 += 1
if C > A:
    tmp = A
    A = C
    C = tmp

if B >= A:
    ans1 += B - A + 1
    B = A - 1

if B <= C:
    ans1 += C - B + 1
    C = B - 1

print(min(ans1, ans2))