package main

import (
	"fmt"
	"math"
)

func MinInt(x, y int) int {
	return int(math.Min(float64(x), float64(y)))
}

func AbsInt(x int) int {
	return int(math.Abs(float64(x)))
}

func resolve(A, B, S int) int {
	if AbsInt(A-S) <= AbsInt(B-S) {
		// Move A
		return AbsInt(A-S) + S
	}
	// Move B + A
	if A == 0 {
		// goto and upto 1st floor
		return AbsInt(B-S) + S + 1
	}
	// goto 1st floor
	tmp1 := AbsInt(B-S) + (S - 1) + A
	// goto A floor
	tmp2 := AbsInt(B-S) + AbsInt(A-S) + A
	return MinInt(tmp1, tmp2)
}

func main() {
	var A, B, S int

	fmt.Scanf("%d %d %d\n", &A, &B, &S)

	fmt.Println(resolve(A, B, S))
}