#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using ulint = unsigned long long int;
using pint = pair<int, int>;
using plint = pair<lint, lint>;
struct fast_ios { fast_ios(){ cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((lint)(x).size())
#define POW2(n) (1LL << (n))
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
template<typename T> istream &operator>>(istream &is, vector<T> &vec){ for (auto &v : vec) is >> v; return is; }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &vec){ os << "["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const deque<T> &vec){ os << "deq["; for (auto v : vec) os << v << ","; os << "]"; return os; }
template<typename T> ostream &operator<<(ostream &os, const set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_set<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T> ostream &operator<<(ostream &os, const unordered_multiset<T> &vec){ os << "{"; for (auto v : vec) os << v << ","; os << "}"; return os; }
template<typename T1, typename T2> ostream &operator<<(ostream &os, const pair<T1, T2> &pa){ os << "(" << pa.first << "," << pa.second << ")"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename TK, typename TV> ostream &operator<<(ostream &os, const unordered_map<TK, TV> &mp){ os << "{"; for (auto v : mp) os << v.first << "=>" << v.second << ","; os << "}"; return os; }
template<typename T> void ndarray(vector<T> &vec, int len) { vec.resize(len); }
template<typename T, typename... Args> void ndarray(vector<T> &vec, int len, Args... args) { vec.resize(len); for (auto &v : vec) ndarray(v, args...); }
template<typename T> bool mjjj(T &m, const T q) { if (m < q) {m = q; return true;} else return false; }
template<typename T> bool mmin(T &m, const T q) { if (m > q) {m = q; return true;} else return false; }
template<typename T1, typename T2> pair<T1, T2> operator+(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first + r.first, l.second + r.second); }
template<typename T1, typename T2> pair<T1, T2> operator-(const pair<T1, T2> &l, const pair<T1, T2> &r) { return make_pair(l.first - r.first, l.second - r.second); }
#define dbg(x) cerr << #x << " = " << (x) << " (L" << __LINE__ << ") " << __FILE__ << endl;
/*
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds; // find_by_order(), order_of_key()
template<typename TK> using pbds_set = tree<TK, null_type, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
template<typename TK, typename TV> using pbds_map = tree<TK, TV, less<TK>, rb_tree_tag, tree_order_statistics_node_update>;
*/

// template< typename T >
// struct edge {
// int src, to;
// T cost;
// //edge(int to) : src(-1),to(to),cost(-1){}
// edge(int to, T cost) : src(-1), to(to), cost(cost) {}
// edge(int src, int to, T cost) : src(src), to(to), cost(cost) {}
// edge &operator=(const int &x) {
// to = x;
// return *this;
// }
// operator int() const { return to; }
// };
// template< typename T >
// using Edges = vector< edge< T > >;
// template< typename T >
// using WeightedGraph = vector< Edges< T > >;
// using UnWeightedGraph = vector< vector< lint > >;
// template< typename T >
// using Matrix = vector< vector< T > >;
// #define INF 1e+9
// #define MAX_V 100000

// // <最短距離, 頂点の番号>
// using P = pair<lint, lint>;

// lint V;
// vector<edge<lint>> G[MAX_V];
// lint d[MAX_V];

// void dijkstra(lint s) {
//     priority_queue<P, vector<P>, greater<P> > que;
//     fill(d, d+V, INF);
//     d[s] = 0;
//     que.push(P(0, s));

//     while (!que.empty()) {
//         P p = que.top();
//         que.pop();
//         lint v = p.second;
//         if (d[v] < p.first) continue;

//         for (lint i=0; i<G[v].size(); ++i) {
//             edge<lint> e = G[v][i];
//             if (d[e.to] > d[v] + e.cost) {
//                 d[e.to] = d[v] + e.cost;
//                 que.push(P(d[e.to], e.to));
//             }
//         }
//     }
// }
lint MAX = 1000000000;
int main(){
    int n;
    cin >> n;
    vector<int> q(n + 1);
    q[1] = 1;
    FOR(i,2,n + 1){
        if(i < 10){
            q[i] = q[i-1] + 1;
        }
        else if(i < 100){
            if(i/10 >= i%10 && i%10 != 0){
                q[i] = q[i-1] + 2;
                if(i/10==i%10){
                    q[i]++;
                }
            }
            else{
                q[i] = q[i-1];
            }
        }
        else{
            int head = i,tail = i%10,digit = 1,ll = 1,lls = 1;
            while(head > 9){
                head /=10;
                digit++;
            }
            REP(j,digit-2){
                ll = ll*10+1;
            }
            REP(j,digit-3){
                lls=lls*10+1;
            }
            if(tail != 0){
                if(head == tail){
                    q[i] = q[i-1] + lls * 2 + (((i-head * (int)pow(10,digit-1) - tail)/10)+1)*2 + 1;
                }
                else if(head > tail){
                    q[i] = q[i-1] + ll * 2;
                }
                else{
                    q[i] = q[i-1] + lls * 2;
                }

            }
            else{
                q[i] = q[i-1];
            }
        }
    }
    cout << q[n];
}

Measured memory_bytes: 1024