---

#!/bin/bash

gcd() {
  local M=$1
  local N=$2
  if [[ $M -eq $N ]]; then
    echo "GCD is $M"
  elif [[ $M -gt $N ]]; then
    gcd $((M - N)) $N
  else
    gcd $M $((N - M))
  fi
}

while true; do
  read -r a b
  if [[ -z $a ]]; then
    echo "bye"
    break
  fi
  gcd $a $b
done