#include<iostream>
#include<fstream>
#include<math.h>
using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");
 
int p,n=0,d=0,c=0;
 
int main()
{
    int aux,i;
    in>>p;
    for(i=1;c<p; i++)
    {
        aux=i;
        while((aux%5==0)&& aux>1)
        if(aux%5==0)
            {
                c++;
                aux/=5;
            }
            
    }
    if(p==0)
    {i=2;}
    out<<(i-1);
    out.close();
    return 0;
     
}