#include <iostream>

using namespace std;

int n,ans = 0;

void dfs(long long 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;
}
