#include<bits/stdc++.h>
using namespace std;
#define int ll
#define ll long long

#define I32_MAX 2147483647
#define I64_MAX 9223372036854775807LL
#define I64_MAX2 1223372036854775807LL
#define INF I64_MAX2
// #define MOD 1000000007
#define MOD 998244353 
#define MEM_SIZE 101010
#define DEBUG_OUT true

#define ALL(x) (x).begin(), (x).end()


template<typename T> void DEBUG(T e){if(DEBUG_OUT == false)return; std::cout << e <<" ";}
template<typename T> void DEBUG(const std::vector<T>& v){if(DEBUG_OUT == false)return;for(const auto& e : v){std::cout<< e << " "; } std::cout << std::endl;}
template<typename T> void DEBUG(const std::vector<std::vector<T> >& vv){if(DEBUG_OUT == false)return;for(const auto& v : vv){ DEBUG(v); } }
template<class T,class... Ts> void DEBUG(T d, Ts... e){if(DEBUG_OUT == false)return;DEBUG(d);DEBUG(e...);}
template <class T> void corner(bool flg, T hoge) {if (flg) {cout << hoge << endl; abort();}}
template< typename T1, typename T2 > inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }
template< typename T1, typename T2 > inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }


//BELOW
void DFS(int val,int n,int &res)
{
  if(val > n)return;
  res += 1;
  DFS(val*10 + 0 , n , res);
  DFS(val*10 + 3 , n , res);
  DFS(val*10 + 6 , n , res);
  DFS(val*10 + 9 , n , res);

  return;
}
bool check(int x)
{
  string str = to_string(x);
  int a = str[0] - '0';
  int b = str[1] - '0';
  if((a+b)%3 == 0) return true;
  return false;
}

void solve(void)
{
  int n;cin>>n;
  int res = 0;
  for (int i = 10; i < min(100LL,n+1); i++)
  {
    if(check(i))res++;
  }
  if(n >= 100)
  {
    res -=12;
    DFS(30,n,res);
    DFS(33,n,res);
    DFS(36,n,res);
    DFS(39,n,res);

    DFS(60,n,res);
    DFS(63,n,res);
    DFS(66,n,res);
    DFS(69,n,res);

    DFS(90,n,res);
    DFS(93,n,res);
    DFS(96,n,res);
    DFS(99,n,res);
  }
  cout<<res<<endl;;

  

  return;
}

int32_t main(int32_t argc, const char *argv[])
{
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);

  std::cout << std::fixed;
  std::cout << std::setprecision(11);
  solve();

  return 0;
}