local mmi, mce = math.min, math.ceil
local n, c, v = io.read("*n", "*n", "*n")
local t = {}
local inf = (c + v) * n
for i = 1, n do t[i] = inf end
t[1] = 0
for i = 1, n - 1 do
  local lim = mce(n / i)
  for j = 2, lim do
    local dst = mmi(n, i * j)
    t[dst] = mmi(t[dst], t[i] + c + (j - 1) * v)
  end
end
print(t[n])