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

typedef long long ll;

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

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