求Sn = a + aa + aaa + aaaa + aaaaa的前五项和，其中a是一个数字，如Sn = 2 + 22 + 222 + 2222 + 22222

#include<stdio.h>
#include<stdlib.h>
int main()
{
int  a = 0, i=0, Sn = 0,tmp=0;
scanf_s("%d", &a);
tmp = a;
Sn = 2;
for (i = 0; i <4; i++)
{
a = a * 10 + tmp;
Sn = Sn + a;
}
printf("%d\n", Sn);

system("pause");
return 0;
}