#include<iostream>
using namespace std;

using ll = long long;
ll n, ans;

void dfs(ll x,int a,int b,int 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);
}

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