求Sn=a+aa+aaa+aaaa+aaaaa的前5项之和，其中a是一个数字，

例如：2+22+222+2222+22222

int main()
{int a;scanf("%d", &a);int n;scanf("%d", &n);int sum = 0;int tmp = 0;for (int i = 0; i < n; i++){tmp = tmp * 10 + a;sum += tmp;}printf("%d", sum);return 0;
}