/**
 * code generated by JHelper
 * More info: https://github.com/AlexeyDmitriev/JHelper
 * @author champon
 */

#include <iostream>
#include <fstream>

#include <bits/stdc++.h>
#define se cout << "test ok" << endl;
#define sp << " " <<
#define enl "\n";
using namespace std;
using ll=long long;
using ld=long double;
ll mod = ll(1e9)+7;
ll inf = ll(1e18);
template<typename T1, typename T2> ll ceill(T1 a, T2 b){ return (a+b-1)/b; }
void ans(bool b, ostream& out=cout){ out << (b ? "Yes" : "No") << endl; }
void ans2(bool b, ostream& out=cout){ out << (b ? "YES" : "NO") << endl; }
template<typename T> inline bool chmax(T &a, T b){ if(a<b){a=b; return true;} return false; }
template<typename T> inline bool chmin(T &a, T b){ if(a>b){a=b; return true;} return false; }
template<typename A, size_t N, typename T> void Fill(A (&array)[N], const T &val){ fill((T*)array, (T*)(array+N), val); }
int dx[] = {1, 0, -1, 0, 1, -1, 1, -1};
int dy[] = {0, 1, 0, -1, 1, -1, -1, 1};

#ifndef INCLUDE_DEBUG_HPP
#define INCLUDE_DEBUG_HPP

#include <iostream>
#include <vector>
#include <map>
using namespace std;

namespace dbg {
    using ll = long long;

    class Debug {
    public:
        Debug(){}
        template<typename T>
        void vd(vector<T> vec);
        template<typename T>
        void vd2(vector<vector<T>> vec);
        template<typename T>
        void ad(T *arr, ll n);
        template<typename T, size_t N>
        void ad2(T (&arr)[N], ll n);
        template<typename T>
        void md(T mp);
    };

    template<typename T>
    void Debug::vd(vector<T> vec) {
        for (auto vv : vec) cout << vv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::vd2(vector<vector<T>> vec) {
        for (auto vv : vec) for (auto vvv : vv) cout << vvv << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::ad(T *arr, ll n) {
        for (int i = 0; i <= n; i++) cout << arr[i] << " ";
        cout << endl;
    }

    template<typename T, size_t N>
    void Debug::ad2(T (&arr)[N], ll n) {
        for (int i = 0; i <= N; i++) for (int j = 0; j <= n; j++) cout << arr[i][j] << " ";
        cout << endl;
    }

    template<typename T>
    void Debug::md(T mp) {
        cout << "key : value" << endl;
        for (auto const &m : mp) cout << m.first << " : " << m.second << endl;
        cout << endl;
    }

}

#endif //INCLUDE_DEBUG_HPP

using dbg::Debug;
Debug debug;

#ifndef DEFINE_PERMUTATION_HPP
#define DEFINE_PERMUTATION_HPP


#include <numeric>
#include <algorithm>

using namespace std;

namespace perm {

    using ll = long long;

    class Perm {
    public:
        int n;
        vector<int> p;

        Perm(int n) : n(n) {}
        void build(int v);
    };

    void Perm::build(int initv = 1) {
        vector<int> v(n);
        iota(v.begin(), v.end(), initv);
        do {
            ll num = 0;
            for(int i=0; i<v.size(); i++){
                // some process
            }
            p.push_back(num);
        } while (next_permutation(v.begin(), v.end()));
    }

}

#endif //DEFINE_PERMUTATION_HPP
using perm::Perm;

class C755 {
public:
    ll n;
    ll res = 0;

    void dfs(const string& s, bool flg){
        if(!s.empty() && stoll(s) > n) return;
        if(!flg) {
            if(s.find('3') != string::npos
            && s.find('5') != string::npos
            && s.find('7') != string::npos){
                flg = true;
                res++;
            }
        }else{
            res++;
        }
        dfs(s + '3', flg);
        dfs(s + '5', flg);
        dfs(s + '7', flg);
    }

	void solve(std::istream& in, std::ostream& out) {
	    in >> n;

	    dfs("", false);

	    out << res << endl;
	}
};


int main() {
	C755 solver;
	std::istream& in(std::cin);
	std::ostream& out(std::cout);
	solver.solve(in, out);
	return 0;
}


Measured memory_bytes: 256