#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,m,n) for(int i=m; i<int(n); ++i)
#define repll(i,m,n) for(ll i=m; i<ll(n); ++i)
#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define fi first
#define se second

template<typename T> bool chmin(T& a, T b){ if(a > b){a = b; return true;} return false; }
template<typename T> bool chmax(T& a, T b){ if(a < b){a = b; return true;} return false; }

template<typename T> T gcd(T a, T b){ return a % b ? gcd(b, a % b) : b; }
template<typename T> T lcm(T a, T b){ return a / gcd(a, b) * b; }

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    ll N;
    cin >> N;

    set<ll> st;
    for(ll i = 12LL; i <= min(100LL, N); i += 3LL){
        string s = to_string(i);
        if(((s[0] - '0') + (s[1] - '0')) % 3 == 0) st.insert(i);
    }

    auto rec = [&](auto rec, ll x) -> void {
        if(x > N) return;
        if(x >= 10LL) st.insert(x);

        if(x) rec(rec, x*10LL + 0LL);
        rec(rec, x*10LL + 3LL);
        rec(rec, x*10LL + 6LL);
        rec(rec, x*10LL + 9LL); 
    };
    rec(rec, 0LL);

    // for(ll s : st) cout << s << endl;
    cout << st.size() << endl;

    return 0;
}