a, b, s = [int(x) for x in input().split()]

a_s = abs(a - s)
b_s = abs(b - s)
res = 0
if b_s < a_s:
    res += b_s
    res += a_s
    res += a
    if a == 0:
        res += 1
else:
    res += a_s + s

print(res)