#include<bits/stdc++.h>
#define ll long long
#define ios ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
#pragma GCC optimize("O3","unroll-loops")
#pragma GCC optimize("Ofast")
using namespace std;
ll kt(ll x)
{
    ll d=0;
    while(x>0)
    {
        d++;
        x/=10;
    }
    return d;
}
ll dem(ll n) {
    ll t = 0;
    for (int i = 1; i <= n; ++i) {
        t+=kt(i);
    }
    return t;
}

int main() {
    ll n;
    cin>>n;
    ll s=dem(n);
    cout<<s;

    return 0;
}