#include <bits/stdc++.h>
using namespace std;
int main() {
  int K, ans;
  cin >> K;
  if (K < 10) {
    cout << K << endl;
    return 0;
  } else {
    ans = 19 + 10 * (K - 10);
  }
  cout << ans << endl;
  return 0;
}
