import java.util.Scanner;


public class qiuhe {


/**
* 
* 求s=a+aa+aaa+aaaa+aa...a的值，
* 其中a是一個數字。例如2+22+222+2222+22222(此時共有5個數相加)，幾個數相加有鍵盤控制。*/


public static void main(String[] args) {
// TODO Auto-generated method stub
long a;
int n;
Scanner scanner=new Scanner(System.in);

System.out.print("請輸入數字a的值：");
a=scanner.nextLong();

System.out.print("請輸入相加的項數：");
n=scanner.nextInt();

System.out.println("s=a+aa+aaa+aaaa+aa...a的和為"+Sum(a, n));
}


public static long Sum(long a,int n) {
long sum = 0,b=0;
int i=0;

while (i<n) {
b+=a;
sum+=b;
a*=10;
i++;
}

return sum;

}
}