#include<stdio.h>
int a[1001],i,k,b[1001],n,j,t,cc;
using namespace std;
int main(){
	freopen("nunta.in","r",stdin);
	freopen("nunta.out","w",stdout);
	scanf("%d",&n);
	a[0]=1;
	a[1]=2;
	for(j=1;j<n-1;j++)
	{
		k=0;
		cc=j;
		while(cc!=0)
		{
			k++;
			b[k]=cc%10;
			cc/=10;
		}
		b[0]=k;
	t=0;
      for(i=1; i<=a[0] || i<=b[0] || t; i++, t/=10)
              a[i] = (t += a[i] + b[i]) % 10;
      a[0] = i - 1;
	}
	for(i=a[0];i>=1;i--)
		printf("%d",a[i]);
	return 0;
}