A,B,S = map(int,input().split())
if abs(S-A)<=abs(S-B):
    print(abs(S-A)+S)
else:
    if S==1 and A>0:
        print(A)
    elif S==1 and A==0:
        print(2)
    elif A>=S:
        print(abs(S-B)+A+min(-S+A,S-1))
    elif 0<A<S:
        print(abs(S-B)+S)
    else:
        print(abs(S-B)+1+S)