Problem:
Score : 400 points

Problem Statement

Snuke has one biscuit and zero Japanese yen (the currency) in his pocket.
He will perform the following operations exactly K times in total, in the order he likes:

Hit his pocket, which magically increases the number of biscuits by one.

Exchange A biscuits to 1 yen.

Exchange 1 yen to B biscuits.

Find the maximum possible number of biscuits in Snuke's pocket after K operations.

Constraints

1 \leq K,A,B \leq 10^9

K,A and B are integers.

Input

Input is given from Standard Input in the following format:

K A B

Output

Print the maximum possible number of biscuits in Snuke's pocket after K operations.

Sample Input 1

4 2 6

Sample Output 1

7

The number of biscuits in Snuke's pocket after K operations is maximized as follows:

Hit his pocket. Now he has 2 biscuits and 0 yen.

Exchange 2 biscuits to 1 yen. his pocket. Now he has 0 biscuits and 1 yen.

Hit his pocket. Now he has 1 biscuits and 1 yen.

Exchange 1 yen to 6 biscuits. his pocket. Now he has 7 biscuits and 0 yen.

Sample Input 2

7 3 4

Sample Output 2

8

Sample Input 3

314159265 35897932 384626433

Sample Output 3

48518828981938099

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
class Program
{
	static void Main(string[] args)
	{

		// スペース区切りの整数の入力
		string[] input = Console.ReadLine().Split(' ');

		int K = int.Parse(input[0]);
		int A = int.Parse(input[1]);
		int B = int.Parse(input[2]);

                int cnt = 0;
                int yen = 0;
                for(int i = 0; i < K; i++){
if(yen >= 1){
cnt = cnt + B;
yen = yen + 1;
} else if(cnt >= A){
cnt = cnt - A;
yen = yen + 1;
} else{
cnt = cnt + 1;
}

                }



		//出力
		Console.WriteLine(cnt + "");
	}
}