#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n;
ll ans = 0;

void dfs(ll x, int a, int b, int c)
{
	if (x > n)
	{
		return;
	}
	if(a&&b&&c) ans++;

	dfs(x * 10 + 7, 1, b, c);
	dfs(x * 10 + 5, a, 1, c);
	dfs(x * 10 + 3, a, b, 1);
}

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