# coding: UTF-8
import sys
#sys.setrecursionlimit(n)
import heapq
import re
import bisect
import random
import math
import itertools
from collections import defaultdict, deque
from copy import deepcopy
from decimal import *

a, b, c = map(int, input().split())
count = 0
if a == 0:
    a += 1
    b += 1
    c += 1
if c == 1:
    count += a
else:
    aa = abs(a - c)
    bb = abs(b - c)
    if aa > bb:
        count += bb
        count += min(aa + c, c - 1 + a)
    else:
        count += aa + c
print(count)