n=gets.to_i
c, v=gets.split.map(&:to_i)

def f(n)
  rt=[]
  (1..n).each do |i|
    break if i*i>n
    if n%i==0
      rt<< i
      rt<< n/i
    end
  end
  rt
end

def g(n)
  rt=Array.new(n+1)
  (1..n).each do |e|
    rt[e]=f(e)
  end
  rt
end

dd=g(2*n)
inf=10**18
dp=Array.new(2*n){inf}
dp[0]=dp[1]=0
(2...(2*n)).each do |i|
  # dd=f(i)
  dd[i].each do |d|
    dp[i]=[dp[i], dp[d]+c+(i-1)/d*v].min
  end
end

puts dp[n...(2*n)].min