#include <fstream>

using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int main()
{
    int p;
    cin>>p;
    if(p==0)
    {
        cout<<1;
        return 0;
    }
    int n=1;
    int nr_fact = 0;
    while(nr_fact<p)
    {
        if(n%5==0)
        {
            int cn=n;
            while(cn!=0 && cn%5==0)
            {
                nr_fact++;
                cn/=5;
            }

        }
        n++;
    }
    cout<<n-1;
    return 0;
}