#include <bits/stdc++.h>

using namespace std;
int nums[1000];

int main() {
    int n;
    string s;
    stringstream ss;
    cin >> n;
    for (int i = 1; i <= n; ++i) {
        ss << i;
        ss >> s;
        ss.clear();
        int sum = 0;
        for (int j = 0; j < s.length(); ++j) {
            sum += (s[j] - 48);
        }
        nums[sum]++;
    }
    int res = 0;
    for (int i = 1; i <= 1000; ++i) {
        if (nums[i]) {
            res += (nums[i] * (nums[i] - 1));
        }
    }
    cout << res + n;
    return 0;
}