#include <iostream>
using namespace std;
unsigned long long a,n,cnt=0;
int d;
void calc(){
    a=1000;d=1;
    while(a*1000<=n){
        a*=1000;
        d++;
    }
    cnt+=d+(n-a)*d;
}

int main(void){
    cin>>n;
    while(n>=1000){
        calc();
        n=a-1;
    }
    cout<<cnt<<endl;
}
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i = 0; i < n; i++)
#define rep2(i, x, n) for(int i = x; i <= n; i++)
#define rep3(i, x, n) for(int i = x; i >= n; i--)
#define each(e, v) for(auto &e: v)
#define pb push_back
#define eb emplace_back
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
#define sz(x) (int)x.size()
using ll = long long;
using pii = pair<int, int>;
using pil = pair<int, ll>;
using pli = pair<ll, int>;
using pll = pair<ll, ll>;
const int MOD = 1000000007;
//const int MOD = 998244353;
const int inf = (1<<30)-1;
const ll INF = (1LL<<60)-1;
template<typename T> bool chmax(T &x, const T &y) {return (x < y)? (x = y, true) : false;};
template<typename T> bool chmin(T &x, const T &y) {return (x > y)? (x = y, true) : false;};

struct io_setup{
    io_setup(){
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        cout << fixed << setprecision(15);
    }
} io_setup;

int main(){
    ll N; cin >> N;

    vector<ll> pw(18, 1);
    rep(i, 17) pw[i+1] = pw[i]*10;

    int K = 0;
    while(N >= pw[K]) K++;

    ll ans = 0;

    rep2(i, 1, K-1){
        ans += (pw[i]-pw[i-1])*((i-1)/3);
    }

    ans += (N+1-pw[K-1])*((K-1)/3);

    cout << ans << '\n';
}