#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

ll n, cou = 0;
void dfs(ll x, int a, int b, int c){
    if(x > n)
        return;
    if(a&b&c)
        cou++;
    dfs(10*x + 3, 1, b, c);
    dfs(10*x + 5, a, 1, c);
    dfs(10*x + 7, a, b, 1);
    return;
}

int main(){
    cin >> n;
    dfs(0,0,0,0);
    cout << cou << endl;
    return 0;
}