求Sn=a+aa+aaa+aaaa+...+aaaaaa...a的值

/*求Sn=a+aa+aaa+aaaa+...+aaaaaa...a的值。其中a是一个数字。例如3+33+333+3333+33333(此时n=5),n由键盘输入*/

#include <stdio.h>int main() {    int a,n;    int i = 1;    int sn = 0;    int tn = 0;      printf("Imput(a,n): ");    scanf("%d %d", &a, &n);//n是个数，a是个数上的数字 比如 n = 2 a = 1表示1+11    while (i <= n){        tn = tn + a;        sn = sn +tn;        a = a * 10;        i++;    }    printf("%d", sn);    return 0;