#include <bits/stdc++.h>
using namespace std;
typedef long long i64;typedef vector<int> ivec;typedef vector<string> svec;

i64 n,ans=0;
void dfs(i64 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;
}
