#include <bits/stdc++.h>
using namespace std;
#define rep2(i,m,n) for (int i = (m); i < (n); ++i)
#define rep(i,n) rep2(i,0,n)
typedef long long int ll;
typedef long double ld;
typedef pair<int, int> P;
template<typename T> struct V : vector<T> { using vector<T>::vector; };
V() -> V<int>;
V(size_t) -> V<int>;
template<typename T> V(size_t, T) -> V<T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<typename T> ostream &operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(20); }; } fast_ios_;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}
const int INF = 1<<30;
const ll LINF = 1LL<<61;

int n;
int func(ll cur)
{
    if(cur > n) return 0;
    //cout << cur << " ";
    int ret = 0;
    if(cur >= 100) ret++;
    if(cur != 0)ret += func(cur * 10);
    ret += func(cur * 10 + 3);
    ret += func(cur * 10 + 6);
    ret += func(cur * 10 + 9);
    return ret;
}

int main()
{
    cin >> n;
    int ans = 0;
    for(int i = 12; i < 100; i+=3)
    {
        if((i/10 + i%10)%3 == 0 && i <= n) ans++;
    }
    ans += func(0);
    cout << ans << endl;

    return 0;
}