#include <fstream>
#include <algorithm>
using namespace std;

int main()
{
    ifstream f("fact.in");
    ofstream g("fact.out");
    unsigned int i,x,p,n0=0;
    f>>p;
    if (p==0) g<<"1\n";
    else
    {
        for (i=5;n0<p;i+=5)
        {
            x=i;
            while (x%5==0&&n0<p)
                x/=5,n0++;
        }
        g<<i-5<<'\n';
    }
    f.close();
    g.close();
    return 0;
}