#include <iostream>
#include <string>
#include <cstdlib>
#include <cmath>
#include <vector>
#include <unordered_map>
#include <map>
#include <set>
#include <algorithm>
#include <queue>
#include <stack>
#include <functional>
#include <bitset>
#include <assert.h>
#include <unordered_map>
#include <fstream>
#include <ctime>
#include <complex>
using namespace std;
typedef long long ll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<char> vc;
typedef vector<string> vs;
typedef vector<bool> vb;
typedef vector<double> vd;
typedef pair<ll,ll> P;
typedef pair<int,int> pii;
typedef vector<P> vpl;
typedef tuple<ll,ll,ll> tapu;
#define rep(i,n) for(int i=0; i<(n); i++)
#define REP(i,a,b) for(int i=(a); i<(b); i++)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
const int inf = 1<<30;
const ll linf = 1LL<<62;
const int MAX = 1020000;
ll dy[8] = {1,-1,0,0,1,-1,1,-1};
ll dx[8] = {0,0,1,-1,1,-1,-1,1};
const double pi = acos(-1);
const double eps = 1e-7;
template<typename T1,typename T2> inline bool chmin(T1 &a,T2 b){
	if(a>b){
		a = b; return true;
	}
	else return false;
}
template<typename T1,typename T2> inline bool chmax(T1 &a,T2 b){
	if(a<b){
		a = b; return true;
	}
	else return false;
}
template<typename T> inline void print(T &a){
    rep(i,a.size()) cout << a[i] << " ";
    cout << "\n";
}
template<typename T1,typename T2> inline void print2(T1 a, T2 b){cout << a << " " << b << "\n";}
template<typename T1,typename T2,typename T3> inline void print3(T1 a, T2 b, T3 c){
	cout << a << " " << b << " " << c << "\n";
}
ll pcount(ll x) {return __builtin_popcountll(x);}
const int mod = 1e9 + 7;
//const int mod = 998244353;

int solve(int n){
	int dp[11][2][2];
	rep(i,10) rep(j,2) rep(k,2) dp[i][j][k] = 0;
	string s = to_string(n);
	int m = s.size();
	dp[0][0][0] = 1;
	rep(i,m){
		int c = s[i] - '0';
		rep(j,c){
			rep(k,2) dp[i+1][j%3==1 || j%3==2][1] += dp[i][0][k];
		}
		rep(k,2){
			dp[i+1][c%3==1 || c%3==2][k] += dp[i][0][k];
		}
		REP(j,c+1,10){
			dp[i+1][j%3==1 || j%3==2][1] += dp[i][0][1];
		}
	}
	return dp[m][0][0] + dp[m][0][1];
}

int main(){
	int n; cin >> n;
	if(n < 100){
		int ans = 0;
		for(int i=10; i<=n; i++){
			if(i % 3 == 0) ans++;
		}
		cout << ans << "\n";
		return 0;
	}
	int ans = solve(n) - solve(99);
	ans += 30;
	cout << ans << "\n";
}