const main = input => {
  const [W, a, b] = input.trim().split(' ').map(x => parseInt(x))
  if (a > b) {
    console.log(Math.max(a - (b + W), 0))
  } else if (a < b) {
    console.log(Math.max(b - (a + W), 0))
  } else {
    console.log(0)
  }
}

// 標準入力
main(require("fs").readFileSync("/dev/stdin", "utf8"))
