N = gets.to_i
C, V = gets.split.map(&:to_i)

dp = Array.new(N + 1, Float::INFINITY)
dp[1] = 0

1.upto(N - 1) do |i|
  1.upto(Rational(N - i, i).ceil) do |j|
    n = i + i * j
    n = N if n > N
    cost = dp[i] + C + j * V
    dp[n] = cost if dp[n] > cost
  end
end

puts dp[N]