//Se da un numar intreg P. Sa se gaseasca cel mai mic numar natural strict pozitiv N
//pentru care N! are exact P cifre de 0 la sfarsit.
//Se stie ca N! = 1 * 2 * 3 * .... * (N - 1) * N.
//0<=p<=10^8
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
long n, i, p, d5=0,nr;
int main()
{   fin>>p;
    if (p==0) fout<<1<<"\n";
    else
    if (p==1) fout<<5<<"\n";
    else
    {
       d5=1;
    for (i=10; ; i=i+5)
    {nr=i;
     while(nr%10==0)
        {
            d5++;
            nr/=10;
        }
     while (nr%5==0)
         {d5++;
          nr/=5;
         }
         if (d5==p) {n=i;break;}

    }

    fout<<n<<"\n";
    }
    fout.close();
    fin.close();
    return 0;
}