A, B, S = map(int, input().split())
ans = 0
# A
if abs(A-S)<=abs(B-S) or S<B<=A:
    ans = abs(A-S)+S
# B
else:
    if A==0:
        ans += 1
        A = 1
    ans += abs(B-S)+A+min(S-1, abs(A-S))

print(ans)