#include<bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define pb push_back
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define srep(i,s,t) for (int i = s; i < t; ++i)
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define uni(x) x.erase(unique(rng(x)),x.end())
#define PQ(T) priority_queue<T,v(T),greater<T> >
#define dup(x,y) (((x)+(y)-1)/(y))
#define v(T) vector<T>
#define vv(T) v(v(T))
using ll = int64_t;
using ull = uint64_t;
using uint = uint32_t;
using pii = pair<int,int>;
using pll = pair<ll,ll>;
using pil = pair<int,ll>;
using pil = pair<int,ll>;
using vi = vector<int>;
using vvi = vector<vi>;
using vl = vector<ll>;
template<typename T>inline istream& operator>>(istream&i,v(T)&v)
{rep(j,v.size())i>>v[j];return i;}
template<typename T>string join(const v(T)&v)
{stringstream s;rep(i,v.size())s<<' '<<v[i];return s.str().substr(1);}
template<typename T>inline ostream& operator<<(ostream&o,const v(T)&v)
{if(v.size())o<<join(v);return o;}
template<typename T1,typename T2>inline istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>inline ostream& operator<<(ostream&o,const pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
constexpr double eps = 1e-6;
constexpr ll LINF = 100200300400500600ll;
constexpr int INF = 2*((1<<30)-1)+1;
//--------------------------------------------------------
#define fastio cin.tie(nullptr); std::ios::sync_with_stdio(false);
#define myio ifstream iofi; if(argc>1){iofi.open(argv[1]); std::cin.rdbuf(iofi.rdbuf());}
#define myloopset int loop = 1; if(argc>2) loop =stoi(argv[2]); rep(i,loop)
//--------------------------------------------------------------
template <class T> T chmin(T &a,T b){if(a>b){a=b; return 1;}else return 0;}
template <class T> T chmax(T &a,T b){if(a<b){a=b; return 1;}else return 0;}
constexpr int dx[4] = {0,1,0,-1};
constexpr int dy[4] = {-1,0,1,0};
// constexpr int mod = 1000000007;
constexpr ll mod = 998244353;

#define Yes(ifeq) cout<<(( ifeq )? "Yes":"No")<<endl;


void Main(){
  ull n_;
  cin>>n_;
  ull n=n_;
  // ull ans=0;g++-10
  ull len=to_string(n).length();
  ull num=1,ans=0;
  for(ull i=1;i<len;i++){
    num*=10;
    ans+=(num-num/(ull)10)*max(((i-(ull)1)/(ull)3),(ull)0);
  }
  ans+=(n+1-num)*((len-(ull)1)/(ull)3);
  cout<<ans<<endl;

} signed main(int argc,char** argv)
{fastio; myio; myloopset Main();}

#include "bits/stdc++.h"
using namespace std;

#define rep(i, a, b) for(int i=a; i<=b; i++)
#define trav(a, x) for(auto& a : x)
#define all(x) begin(x), end(x)
#define sz(x) (int) x.size()
#define pb push_back
#define f first
#define s second
#define nl "\n"
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
const int MOD = 1e9+7;
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;

// int dp[101][2];
int a, b, x, y;

int main(){
  ios::sync_with_stdio(false);
  cin.tie(0);
  // freopen("input.txt", "r", stdin); 
  // freopen("output.txt", "w", stdout);

  cin >> a >> b >> x >> y;
  cout << (a==b?x:min(a>b?(a-b-1)*y+x:(b-a)*y+x, (a>b? (a-b)*(2*x)-x: (2*b-2*a+1)*x)));
}