#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;
    
}
