#include <iostream>
#include <fstream>
using namespace std;
ifstream fin("fact.in");
ofstream fout("fact.out");
unsigned long long  p,n,c,prod,i,aux;
unsigned long long iesi ()
{
    return 0;
}
void tip ()
{
    fout<<n;
    iesi();

}
int main()
{
    fin>>p;
    n=1;
    prod=1;
    while(c!=p)
    {
        c=0;
        if(n==2||n==5||n==10)
            prod=prod*n;
        aux=prod;
        while(aux%10==0)
        {
            aux/=10;
            c++;
        }
        if(c==p)
            tip();
        n++;
    }
    return 0;
}