#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define REP(i,n) for(int i=0,_n=(int)(n);i<_n;++i)
#define ALL(v) (v).begin(),(v).end()
#define CLR(t,v) memset(t,(v),sizeof(t))
template<class T1,class T2>ostream& operator<<(ostream& os,const pair<T1,T2>&a){return os<<"("<<a.first<<","<<a.second<< ")";}
template<class T>void pv(T a,T b){for(T i=a;i!=b;++i)cout<<(*i)<<" ";cout<<endl;}
template<class T>void chmin(T&a,const T&b){if(a>b)a=b;}
template<class T>void chmax(T&a,const T&b){if(a<b)a=b;}

ll nextLong() { ll x; scanf("%lld", &x); return x;}

vector<int> f(int N) {
  vector<int> res;
  while (N > 0) {
    res.push_back(N % 10);
    N /= 10;
  }
  reverse(ALL(res));
  return res;
}

int main2() {
  int N = nextLong();

  ll ans1 = 0;
  for (int n = 10; n <= 99; n++) {
    if (n <= N) {
      int a = n % 10;
      int b = n / 10;
      if ((a % 3 == 1 && b % 3 == 2) ||
          (a % 3 == 2 && b % 3 == 1)) {
            ans1++;
          }
    }
  }
  auto v = f(N);
  ll dp[10][2] = {};
  dp[0][0] = 1;
  for (int i = 0; i < (int)v.size(); i++) {
    for (int d : {0, 3, 6, 9}) {
      if (d < v[i]) {
        dp[i+1][1] += dp[i][0];
        dp[i+1][1] += dp[i][1];
      } else if (d == v[i]) {
        dp[i+1][0] += dp[i][0];
        dp[i+1][1] += dp[i][1];
      } else {
        dp[i+1][1] += dp[i][1];
      }
    }
  }

  ll ans2 = dp[v.size()][0] + dp[v.size()][1];
  ans2 -= 4;
  ll ans = ans1 + ans2;
  cout << ans << endl;
  return 0;
}

int main() {

#ifdef LOCAL
  for (;!cin.eof();cin>>ws)
#endif
    main2();
  return 0;
}