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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
typedef long long ll;
ll max(ll x, ll y) {
	return x > y ? x : y;
}
int main() {
	int k, a, b, yen = 0;
	scanf("%d%d%d", &k, &a, &b);
	ll ans = k + 1, num = 1;
	for (int i = 0; i < k; i++) {
		if (yen == 1) {
			num += b;
			yen--;
		} else if (num < a) {
			num++;
		} else {
			num -= a;
			yen++;
		}
	}
	if (yen == 1) {
		num += a + 1;
	}
	printf("%lld\n", max(ans, num));
	return 0;
}