#include <iostream>
#include <algorithm>
#include <map>
#include <set>
#include <queue>
#include <stack>
#include <numeric>
#include <bitset>
#include <cmath>

static const int MOD = 1000000007;
using ll = long long;
using u32 = unsigned;
using u64 = unsigned long long;
using namespace std;

template<class T> constexpr T INF = ::numeric_limits<T>::max()/32*15+208;

int main() {
    int n;
    cin >> n;
    int ans = 0;
    array<int, 4> v{0, 3, 6, 9};
    for (int i = 12; i <= min(99, n); i += 3) {
        ans++;
    }
    for (int i = 0; i < (1 << 18); ++i) {
        int val = 0;
        int x = 1;
        for (int j = 0; j < 9; ++j) {
            val += v[(3 << (2*j) & i) >> (2*j)]*x;
            x *= 10;
        }
        if(val <= n && val >= 100) ans++;
    }
    cout << ans << "\n";
    return 0;
}