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: Wrong Answer)

#include <stdio.h>

int main(){
    long k, a, b;
    long bis = 1;
    long i=1, yen =0,max;
    scanf("%ld%ld%ld",&k,&a,&b);

        while(yen+i<=k){
            if(bis == a){
                yen++;
                bis = 0;
                i++;
            }else{
                bis++;
                i++;
            }
        }
        bis += yen * b;
        max = bis;
    bis = i = 1;
    yen = 0;
        bis = a;
        i += a-1;
        if(i%2==1){
            bis++;
            i++;
        }
        for (; i<k; i+=2){
            bis += b-a;
        }
    if(max < bis){
        max = bis;
    }
    bis = i = 1;
    yen = 0;
        bis = 1+k;
    if(max < bis){
        max = bis;
    }
    printf("%ld\n",max);
    return 0;
}