class BinaryMath {
  static sum(a, b) {
    let carry = (a & b)
    carry = carry << 1
    return carry === 0 
      ? b
      : this.sum(carry, b)
  }
  
  static sub(a, b) {
    let carry = (~a) & b
    b = a ^ b
    carry = carry << 1
    return carry === 0 
      ? b
      : this.sum(carry, b)
  }
  
  static mul(a, b) {
    let carry = 0
    while(b > 0) {
      if(b & 1) {
        carry = this.sum(carry, a)
      }
      a <<= 1
      b >>= 1
    }
    return carry
  }
  
  static div(a, b) {
    let quotient = 0
    let remainder = a
    while(remainder >= b) {
      let shift = 0
      while(remainder >= (b << shift)) {
        shift++
      }
      shift--
      quotient |= (1 << shift)
      remainder = this.subtract(remainder, b << shift)
    }
    return quotient
  }
}