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

long long n, ans = 0;

void dfs(long long x, long long a, long long b, long long c){
    if(x > n){
        return ;
    }
    if(a && b && c){
        ans++;
    }
    dfs(x * 10 + 3, 1, b, c)
    dfs(x * 10 + 5, a, 1, c)
    dfs(x * 10 + 7, a, b, 1)
}

signed main(){
    cin >> n;
    dfs(0, 0, 0, 0);

    cout << ans << endl;
    return 0;
}