@h,@a,@d=gets.split.map{|e|e.to_i}


@dp = Array.new(10005,100000.0)

def dfs(hp=0,c=0.0)
  i=[@h,hp].min
  @dp[i]=[@dp[i],c].min
  return if @h <= hp
  dfs(hp+@d,@dp[i]+1.5)
  dfs(hp+@a,@dp[i]+1.0)
end

dfs

p @dp[@h].to_f