11864번 - Game 서브태스크다국어

John and George play the following game: John chooses one integer x in the set A_n = {1, 2, 3, … , n}. George has to guess the value of x. Players play by consecutive moves = 1, 2, … . In the k-th move of the game, George chooses a subset B_k of A_n and John says YES, if x belongs to B_k or NO, otherwise. In case of answer NO, George pays John a euros; in case of answer YES, George pays John b euros. We want to know the minimum amount of euros that George has to pay in order to find x, regardless of John's choice.

Write a program game that calculates the wanted minimum amount.

On the first line of the standard input are given three integers n, a, and b, separated by a space. 

On the standard output, print out one integer, that is equal to the wanted minimum amount of euros. 

• 1 < n < 10¹⁸
• 0 < a, b < 1 000

George can find x for 4 euros, in the following way:

George selects set B₁ = {1, 2}.

• If John’s answer is YES, George pays 2 euros and then selects set B₂ = {1}. If the next answer is YES, George pays another 2 euros and the game ends (the chosen integer was 1), otherwise he pays another 1 euro and the game ends (the chosen integer was 2).
• If John’s answer is NO, George pays 1 euro and selects the set B₂ = {3}. If the next answer is YES, George pays another 2 euros and the game ends (the chosen integer was 3), otherwise he pays another 1 euro and selects the set B₃ = {4}. If the last answer is YES, George pays another 2 euros and the game ends (the chosen integer was 4), otherwise George pays another 1 euro and the game ends (the chosen integer was 5).