/*#include <fstream>

using namespace std;

int main()
{
    unsigned n,i,x,y;
    ifstream fin("euclid2.in");
    ofstream fout("euclid2.out");
    fin>>n;
    for(i=1;i<=n;i++)
    {
        fin>>x>>y;
        {
            while(x!=y)
            {
            if(x>y)
                x=x-y;
            else
                y=y-x;
            }
        fout<<x<<'\n';
        }
    }

    fin.close();
    fout.close();
    return 0;

}*/

#include<fstream>
using namespace std;
int main()
{

    unsigned p,i=5,nr=1,aux;
    ifstream fin("fact.in");
    ofstream fout("fact.out");
    fin>>p;
    while(nr<p)
    {
        i=i+5;
        aux=i;
        while(aux%5==0)

			{ nr++;
                if(nr==p)
                {
                    fout<<i;
                    fin.close();
                    fout.close();
                    return 0;
                }
			  aux=aux/5;
			}

    }

    fout<<i;
    fin.close();
    fout.close();
	return 0;

}
/*#include<fstream>
#include<cmath>
using namespace std;

int main()
{
	unsigned i,n,l, s=0,r,c,x;
	ifstream fin("cifra.in");
	ofstream fout("cifra.out");
	fin>>n;
	for(l=1;l<=n;l++)
	{
	    fin>>x;
        for(i=1;i<=x;i++)
        {
            r=i%4;
            if(r%4)

            else
                c=pow(r,r);
            s=s+c%10;
        }

	 fout<<s%10<<'\n';
	}
	fin.close();
	fout.close();

	return 0;
}*/