#include<iostream>
#include<fstream>
using namespace std;
int main ()
{
    ifstream cin("fact.in");
    ofstream cout("fact.out");
    int p;
    cin>>p;
    int f=1;long x=1;
    while(p!=0)
        {
        x=x*10;
        p=p-1;
        }
    long long i=1;
    for(i=1;i<=100000000;i++)
        {
        f=f*i;
        if(f%x==0)
            {
            cout<<i;
            break;
        }

        }
        return 0;
}