#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define rep(i,n) for(ll i=0;i<(n);i++)
#define pll pair<ll,ll>
#define pii pair<int,int>
#define pq priority_queue
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define endl '\n'
#define ios ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define lb(c,x) distance(c.begin(),lower_bound(all(c),x))
#define ub(c,x) distance(c.begin(),upper_bound(all(c),x))

using namespace std;

inline int topbit(unsigned long long x){
	return x?63-__builtin_clzll(x):-1;
}

inline int popcount(unsigned long long x){
	return __builtin_popcountll(x);
}

inline int parity(unsigned long long x){//popcount%2
	return __builtin_parity(x);
}



template<class T> inline bool chmax(T& a,T b){if(a<b){a=b;return 1;}return 0;}
template<class T> inline bool chmin(T& a,T b){if(a>b){a=b;return 1;}return 0;}

const ll INF=1e9+7;

vector<ll> ans;

void dfs(ll num,ll cnt){
    if(cnt==9) ans.push_back(num);
    else{
        rep(i,4){
            dfs(num*10+3*i,cnt+1);
        }
    }
    return ;
}

int main(){
    ll n;
    cin >> n;
    if(n<100){
        cout << n/3-10/3 << endl;
    }
    else{
        dfs(0,0);
        sort(ans.begin(),ans.end());
        ll sum=0;
        map<ll,ll> m;
        for(auto x:ans){
            if(x>100 && x<=n && m.count(x)==false){
                sum++;
                m[x]++;
            }
        }
        cout << sum+100/3-10/3 << endl;
    }
    return 0;
}