Problem:
Score : 100 points

Problem Statement

There is a hotel with the following accommodation fee:

X yen (the currency of Japan) per night, for the first K nights

Y yen per night, for the (K+1)-th and subsequent nights

Tak is staying at this hotel for N consecutive nights.
Find his total accommodation fee.

Constraints

1 \leq N, K \leq 10000

1 \leq Y < X \leq 10000

N,\,K,\,X,\,Y are integers.

Input

The input is given from Standard Input in the following format:

N
K
X
Y

Output

Print Tak's total accommodation fee.

Sample Input 1

5
3
10000
9000

Sample Output 1

48000

The accommodation fee is as follows:

10000 yen for the 1-st night

10000 yen for the 2-nd night

10000 yen for the 3-rd night

9000 yen for the 4-th night

9000 yen for the 5-th night

Thus, the total is 48000 yen.

Sample Input 2

2
3
10000
9000

Sample Output 2

20000

Solution in C (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<stdio.h>
int main()
{
    int n,h,k,p,l,g;
    scanf("%d",&n);
         if(n==1){
            k=10000;
        printf("%d\n",k);}
     else if(n==2){
            k=20000;
            printf("%d\n",k);}
              else if(n==3){
            k=30000;
        printf("%d\n",k);}
        else if(n>3)

        {
            k=30000;
            p=(n-3);
            h=(p*9000)+k;
            printf("%d\n",h);

        }
}