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

int main(void){
  long N;
  cin >> N;
  long a = 1000000000;
  long n = N - 7;
  if(N == a){
    cout << 0 << endl;
    return 0;

  }
  if(n > a){
    cout << log10(n / a) << endl;
    return 0;

  }
  cout << log10(a / n) << endl;
  return 0;

}