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

#define p(x) cout << x << endl;
#define el cout << endl;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    long a = 1000000000;
    long n;
    cin >> n;
    n -= 7;

    int b;
    int count = 0;

    if(n > a){
        b = n / a;
        // cout << b << endl;
    }else{
        b = a / n;
        // cout << b << endl;
    }

    while(true){
        b = b / 10;
        count++;
        if(b < 10){
            break;
        }
    }

    cout << count << endl;
}