#include <iostream>
#include <fstream>
using namespace std;
long n,i,j,sol,p;
int main()
{
const long pcrit[14] = {1,6,31,156,781,3906,19531,97656,488281,2441406,12207031,61035156,305175781,1525878906};
ifstream in("fact.in");
in >> n;
//if (((n+1) % 6)==0)
//    sol=-1;
//
//else
{
p=1220703125;
i=13;
do

if (pcrit[i]>n)
    {
        i--;
        p=p/5;
    }
else
    {
        n=n-pcrit[i];
        sol=sol+p;
    }
while (n>0);
sol=sol*5;
}
ofstream out("fact.out");
out << sol;
out.close();
return 0;
}