#include <bits/stdc++.h>

namespace solver{
  std::unordered_set<int> set;
  
  void dfs(int i, int s, int N){
    if(i == 9){
      if(s <= N and s >= 100) set.insert(s);
      return;
    }

    dfs(i + 1, s * 10 + 0, N);
    dfs(i + 1, s * 10 + 3, N);
    dfs(i + 1, s * 10 + 6, N);
    dfs(i + 1, s * 10 + 9, N);
  }
  
  void solve(){
    int N; std::cin >> N;

    int ans = 0;

    for(int i = 10; i <= 99; ++i){
      if(i <= N){
        if(i % 3 == 0){
          if(((i % 10) + (i / 10)) % 3 == 0){
            ++ans;
          }
        }
      }
    }

    dfs(0, 0, N);
    ans += set.size();

    std::cout << ans << "\n";
  }
}

int main(){
  solver::solve();
  return 0;
}