#include <fstream>
#include <bitset>

using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
bitset <1000000001>a;
long long x,nr,i,p,putere;
int main()
{
    f>>p;


    for (i=5;i<=1000000000;i*=5)
     a[i]=1;

     putere=1;
     nr=0;

    while (nr<p)
     {
          x+=5;
         if (a[x]==0)
          nr++;
         else
          {
              nr+=putere;
              putere++;
          }


     }
     g<<x;
    f.close();
    g.close();
}