#include <iostream>
#include <iomanip>
#include <algorithm>
#include <array>
#include <cassert>
#include <utility>
#include <vector>

long long int to(int d){
    long long int res = 0;
    for(long long int mv = 3; d > 0; mv *= 10, d /= 4) res += (d % 4) * mv;
    return res;
}

int main(void){
    std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); 
    std::cout << std::fixed << std::setprecision(16);

    int n; std::cin >> n;
    int ok = 0, ng = (1 << 20) + 1;
    while(ng - ok > 1){
        const int mid = (ng + ok) >> 1;
        const long long int v = to(mid);
        if(v <= n) ok = mid; else ng = mid;
    }
    int res = ok - 3; for(int x = 12; x <= 100 and x <= n; x += 3){
        if( (x % 10) % 3 != 0 ) ++res;
    }
    std::cout << res << '\n';
    return 0;
}