class Binary {
  field boolean head
  field Binary tail

  constructor(int n) {
    this.head := n / 2 * 2 != n;
    if (n > 1) then this.tail := new Binary(n / 2)
  }

  method String toString()
    if (this.tail != nil & this.head) then return this.tail.toString().concat(1)
    else if (this.tail != nil) then return this.tail.toString().concat(0)
    else if (this.head) then return "1"
    else return "0"

  method void main()
    new Binary(815).toString().concat("\n").output()
}