#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main()
{
    int n;
    cin >> n;

    int real_numbers = 0;
    for(int i = 1; i <= n; i++) {

        int tmp = i;
        bool ok = true;
        while(tmp > 0) {
            int digit = tmp % 10;
            if(digit == 7) {
                ok = false;
                break;
            }
            tmp /= 10;
        }
        if(ok) {
            real_numbers++;
        }
    }
    cout << real_numbers << endl;

    return 0;
}