#include <bits/stdc++.h>
#define FOR(i, a, n) for(ll i = (ll)a; i < (ll)n; i++)
#define FORR(i, n) for(ll i = (ll)n - 1LL; i >= 0LL; i--)
#define rep(i, n) FOR(i, 0, n)
#define ALL(x) begin(x), end(x)
using namespace std;
using ll = long long;
constexpr ll Mod = 998244353;
constexpr ll mod = 1e9 + 7;
constexpr ll inf = 1LL << 60;
const double PI = acos(-1);
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);
}
/*-------------------------------------------*/

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

    ll n;
    cin >> n;

    int cnt = 0;
    rep(i, 1 << 20) {
        ll x = 0;
        rep(j, 10) {
            int a = (i >> (j << 1)) & 3;
            x *= 10;
            x += a * 3;
        }
        if(100 <= x && x <= n) cnt++;
    }

    FOR(i, 10, 100)
    if(i % 3 == 0 && i <= n) cnt++;

    cout << cnt << endl;

    return 0;
}