A, B, S = map(int, input().split())

diffA = abs(A - S)
diffB = abs(B - S)
distance = 0

if A == 0:
    if diffA <= diffB :
        distance = diffA + S
    else:
        distance = 1 + diffB + S

elif A >= S :
    if diffA <= diffB :
            distance = diffA + S
    else :
        distance = diffB + S - 1 + A

elif A < S:
    if diffA <= diffB :
        distance = diffA + S
    else :
        distance = diffB + S

print(distance)