# coding:utf-8

A, B, S = map(int, input().split())
ans = 0
if abs(A-S)<=abs(B-S):
    ans = abs(A-S)+S
# ここからB
else:
    if A==0:
        ans += 1
        A = 1
    ans += abs(B-S)+A+min(S-1, abs(A-S))
# elif S>A:
#     if A==0:
#         ans += 1
#         A = 1
#     ans += abs(B-S)+abs(A-S)+A
# else:
#     ans = abs(B-S)+A+min(S-1, abs(A-S))
print(ans)