# 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
off = 0
if a == 0:
    a += 1
    b += 1
    c += 1
    off = 1
if c == 1 + off:
    count += a + off
else:
    aa = abs(a - c) + off
    bb = abs(b - c) + off
    if aa > bb:
        count += bb
        count += min(a + c - 1 + off, aa + a + off)
    else:
        count += aa + c + off
print(count)