import java.lang.System.*;
import java.util.Scanner;


public class file{
    public static void main (String[]args){
        Scanner sc = new Scanner(System.in);
        int a,b,c,d,e,r,sum,x;
        a = sc.nextInt();
        b = sc.nextInt();
        c = sc.nextInt();
        d = sc.nextInt();
        e = sc.nextInt();
        sum=d;
        r = d;
        x=d;
        if(b-c!=0){
            for(int i=2;i<=a*(b-c);i++){
                if(i%10!=0){
                    r= x;
                    sum+=r;
                    x=r;
                }else if(i%10==0&&e<=x){
                    r=x-e;
                    sum+=r;
                    x=r;
    
                }else if(i%10==0&&e>x){
                    r=x;
                    sum+=r;
                    x=r;
                }

        }
        } else {
            sum=0;
        }
        System.out.println(sum);

    }
}