#include<bits/stdc++.h>
#define int long long
#define BASIC 27000000
using namespace std;
int n,ans,pre[1003];
int work(int x){
	int now=0;
	while(x){
		now+=x%10;
		x/=10;
	}
	return now;
}
signed main(){
	pre[0]=0;
	for(int i=0;i<1000;++i) pre[i+1]=pre[i]+(i/10+i%10)*1000000+BASIC;
	scanf("%lld",&n);
	ans+=pre[n/1000000];
	for(int i=n-n%1000000;i<=n;++i) ans+=work(i);
	printf("%lld",ans);
	return 0;
}