#include <iostream>
#include <fstream>
using namespace std;
 
ifstream f;
ofstream g;
 
long int n,k,p,i;
 
main()
{
 
f.open("fact.in");
g.open("fact.out");
 
f>>p;
n=0;
k=0;

n=p*5;

k=5;
i=0;
while(k<n){
           k*=k;
           i++;
           }
n=n-(i-1)*5;

if(n==0)g<<"1";
else g<<n;
g.close();
}