#include <fstream>
using namespace std;
ifstream cin("fact.in");
ofstream cout("fact.out");
int main()
{
    int n,s=0,x=0;
    cin>>n;
    if(n==0)
    {
        cout<<1;
    }
    else
    {
        while(x<=n)
        {
            s+=5;
            int cs=s;
            int l=0;
            while(cs%5==0)
            {
                l++;
                cs/=5;
            }
            x+=l;
        }
        cout<<s-5;
    }
    return 0;
}