#include <fstream>
using namespace std;

int main()
{
    long long n,c=0,d=0,aux;
    ifstream f("fact.in");
    ofstream g("fact.out");
    f>>n;
    if(n==0)
      g<<1;
    else
    {
    while(c<n)
    {
        d=d+5;
        aux=d;
        while(aux%5==0)
          {
              c++;
              aux=aux/5;
          }
    }
    g<<d;
    }
    return 0;
}