#include <bits/stdc++.h>
#define range(i, l, r) for(long long int (i) = (l); (i) < (r); (i)++)
#define reversed_range(i, l, r) for (long long int (i) = (r) - 1; (i) >= l; (i)--)
using namespace std;
template <typename T>
using vec = vector<T>;
using lint = long long;
using ulint = unsigned long long;
using pint = pair<int, int>;
using plint = pair<lint, lint>;

template <typename S, typename T>
ostream& operator <<(ostream& os, pair<S, T> p) {
    os << "(";
    os << p.first << ", " << p.second;
    return os << ")";
}

template <typename T>
ostream& operator <<(ostream& os, vec<T> v) {
    os << "[";
    if (v.size() == 0) return os << "]";
    for (int i = 0; i < v.size() - 1; i++) {
        os << v.at(i) << ", ";
    }
    return os << v.at(v.size() - 1) << "]";
}

template <typename T>
ostream& operator <<(ostream& os, set<T>& s) {
    os << "{";
    if (s.begin() == s.end()) return os << "}";
    auto it_first_item = s.begin();
    os << *it_first_item;
    for (auto it = ++it_first_item; it != s.end(); it++) {
        os << ", " << *it;
    }
    return os << "}";
}

template <typename T>
ostream& operator <<(ostream& os, unordered_set<T>& s) {
    os << "{";
    if (s.begin() == s.end()) return os << "}";
    auto it_first_item = s.begin();
    os << *it_first_item;
    for (auto it = ++it_first_item; it != s.end(); it++) {
        os << ", " << *it;
    }
    return os << "}";
}

template <typename K, typename V>
ostream& operator <<(ostream& os, map<K, V> m) {
    os << "{";
    if (m.begin() == m.end()) return os << "}";
    auto it_first_item = m.begin();
    os << it_first_item->first << ": " << it_first_item->second;
    for (auto it = ++it_first_item; it != m.end(); it++) {
        os << ", " << it->first << ": " << it->second;
    }
    return os << "}";
}

template <typename K, typename V>
ostream& operator <<(ostream& os, unordered_map<K, V> m) {
    os << "{";
    if (m.begin() == m.end()) return os << "}";
    auto it_first_item = m.begin();
    os << it_first_item->first << ": " << it_first_item->second;
    for (auto it = ++it_first_item; it != m.end(); it++) {
        os << ", " << it->first << ": " << it->second;
    }
    return os << "}";
}

lint pow(lint num, lint e, lint MOD) {
    lint res = 1;
    lint cur_num = num;
    while (e) {
        if (e & 1) {
            res *= cur_num;
            res %= MOD;
        }
        cur_num *= cur_num;
        cur_num %= MOD;
        e >>= 1;
    }
    return res;
}

int main() {
    cin.tie(0); cout.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    lint N; cin >> N;
    lint ans = 0;
    auto extract_edge_digits = [](lint num) {
        lint tail = num % 10;
        while (num >= 10) {
            num /= 10;
        }
        return make_pair(num, tail);
    };
    auto num_digits = [](lint num) {
        lint ans = 0;
        while (num) {
            ans += 1;
            num /= 10;
        }
        return ans;
    };
    lint n_digits_N = num_digits(N);
    vec<lint> pow_10(n_digits_N + 1, 1);
    range(i, 1, n_digits_N + 1) pow_10.at(i) = pow_10.at(i - 1) * 10;
    lint head_N = N / pow_10.at(n_digits_N - 1), tail_N = N % 10;
    lint middle_N = N % pow_10.at(n_digits_N - 1) / 10;
    // cout << head_N << " " << tail_N << "\n";
    range(A, 1, N + 1) {
        lint head, tail;
        tie(head, tail) = extract_edge_digits(A);
        if (tail == 0) continue;
        if (head == tail) {
            // start with 1 digit
            if (head <= N) ans += 1;
        }
        range(n_digits_bet, 0, n_digits_N - 1) {
            if (n_digits_bet + 2 < n_digits_N) ans += pow_10.at(n_digits_bet);
            else {
                if (tail < head_N) ans += pow_10.at(n_digits_bet);
                else if (tail == head_N) ans += (head <= tail_N ? middle_N + 1: middle_N);
            }
        }
    }
    cout << ans << "\n";
}

Measured memory_bytes: 256