#define _USE_MATH_DEFINES
#include <bits/stdc++.h>
using namespace std;
#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
using ll = long long;
const int INF = 0x3f3f3f3f;
const ll LINF = 0x3f3f3f3f3f3f3f3fLL;
const double EPS = 1e-8;
const int MOD = 1000000007;
// const int MOD = 998244353;
const int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1};
const int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1};
template <typename T, typename U> inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; }
template <typename T, typename U> inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; }
struct IOSetup {
  IOSetup() {
    cin.tie(nullptr);
    ios_base::sync_with_stdio(false);
    cout << fixed << setprecision(20);
  }
} iosetup;

int main() {
  int n; cin >> n;
  int ans = 0;
  for (int i = 12; i <= 99 && i <= n; i += 3) ++ans;
  vector d{0, 3, 6, 9};
  vector<vector<int>> pen(10);
  for (int x : d) {
    if (x == 0) continue;
    for (int y : d) for (int z : d) {
      pen[3].emplace_back(x * 100 + y * 10 + z);
    }
  }
  FOR(i, 4, 10) {
    for (int e : pen[i - 1]) for (int f : d) pen[i].emplace_back(e * 10 + f);
  }
  FOR(i, 3, 10) {
    for (int e : pen[i]) ans += e <= n;
  }
  cout << ans << '\n';
  return 0;
}