#include <stdio.h>
int main () 
{
    int i,n,a,s1=a,f1=a,f2=0;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
      {
          s1=s1+f2;
          f2=f1*10+a;
          f1=f2;
      }
    printf("s1=%d\n",s1);
    return 0;
}