#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define ld long double
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define lb lower_bound
#define ub upper_bound
#define loop(i,a,b) for(ll i=a;i<b;i++)
#define inf (long long int) 1e18
#define eps 0.000001
#define vl vector<ll> 
#define sl set<ll>
#define pll pair<ll, ll>
#define mll map<ll, ll> 
#define mod 1000000007
#define MAXN 15000001
ll spf[MAXN]; 
ll gcd(ll a,ll b);
ll palindrome(string s);
ll modexp(ll a,ll b,ll m);
void sieve();
ll ceil(ll a, ll b);
sl getFactorization(ll x);
void getZarr(string str, ll Z[]);

ll n;
vl ans;
vl v;
void f(ll x, ll dig){
    //cout<<"function "<<x<<" "<<dig<<endl;
    if(v.size()==dig){
        /*cout<<v.size()<<endl;
        for(auto x:v) cout<<x;
        cout<<endl;*/
        ll as=0, th=0, fi=0, se=0;
        loop(i,0,v.size()){
            if(v[i]==3) th++;
            else if(v[i]==5) fi++;
            else if(v[i]==7) se++;
            as=as+(v[i]*pow(10,v.size()-i-1));
        }
        if(as<=n && th>0 && fi>0 && se>0) ans.pb(as);
        //v.clear();
    }
    else {
        v.pb(3);
        f(x-1,dig);
        v.pop_back();
        v.pb(5);
        f(x-1,dig);
        v.pop_back();
        v.pb(7);
        f(x-1,dig);
        v.pop_back();
    }
    
}

int main(){
    ios::sync_with_stdio(0);
    cin.tie(0);
    /*#ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin);
        freopen("output.txt", "w", stdout);
    #endif*/

    
    cin>>n;
    ll dig=0;
    ll dum=n;
    while(dum>0){
        dum=dum/10;
        dig++;
    }
    //cout<<dig<<endl;
    loop(i,3,dig+1){
        f(i,i);
    }
    cout<<ans.size()<<endl;


}

ll gcd(ll a, ll b){
    if (a == 0)   return b;
    if(b==0)      return a;
    if (a == b)   return a;
    if (a > b)    return gcd(a%b, b);
    return gcd(a, b%a);
}

ll palindrome(string s){
    ll l = 0;
    ll h = s.length() - 1;
    while (h > l){
        if (s[l++] != s[h--]){
            return 0;
        }
    }
    return 1;
}

ll modexp(ll a, ll b, ll m){
    if (b==0)
        return 1;
    ll temp = modexp(a,b/2,m);
    temp = (temp*temp)%m;
    if (b&1)
        return (temp*(a%m))%m; // if b is odd a^b = a^(b/2)*a^(b/2)*a
    return temp;
}

void sieve() { 
    spf[1] = 1; 
    for (ll i=2; i<MAXN; i++) 
        spf[i] = i; 
    for (ll i=4; i<MAXN; i+=2) 
        spf[i] = 2; 
  
    for (ll i=3; i*i<MAXN; i++) { 
        if (spf[i] == i) { 
            for (ll j=i*i; j<MAXN; j+=i) 
                if (spf[j]==j) 
                    spf[j] = i; 
        } 
    } 
} 

sl getFactorization(ll x) 
{ 
    sl ret; 
    while (x != 1) 
    { 
        ret.insert(spf[x]); 
        x = x / spf[x]; 
    } 
    return ret; 
} 

ll ceil(ll a,ll b){
    return a/b+(a%b!=0);
}

void getZarr(string str, ll Z[]){
    ll n = str.length();
    ll L, R, k;
    L = R = 0;
    for (ll i = 1; i < n; ++i){
        if (i > R){
            L = R = i;
            while (R<n && str[R-L] == str[R])
                R++;
            Z[i] = R-L;
            R--;
        } else {
            k = i-L;
            if (Z[k] < R-i+1)
                Z[i] = Z[k];
            else {
                L = i;
                while (R<n && str[R-L] == str[R])
                    R++;
                Z[i] = R-L;
                R--;
            }
        }
    }
}

Measured memory_bytes: 640