#include <bits/stdc++.h>
#define INF 5000000000000000000
#define ll long long
#define pll pair<ll, ll>
using namespace std;

int main() {
  //9 + 81 + 81 + 81....
  ll N;
  cin >> N;
  vector<pll> pos;
  for (ll i = 1; i <= 9; ++i) {
    for (ll j = i + 1; j <= 9; ++j) {
      pos.push_back({i, j});
    }
  }
  N -= 1;//0index
  ll X = N / (ll)pos.size() + 1;
  N %= (ll)pos.size();
  ll a = pos.at(N).first, b = pos.at(N).second;
  string ans = to_string(a);
  for (ll i = 0; i < X; ++i) {
    ans += (char)('0' + b);
  }
  cout << ans << endl;
}