#include <iostream>
#include <fstream>
using namespace std;
int main()
{
	ifstream input("factorial.in");
	long long int p;
	input>>p;
	input.close();
	long long int n=0,contor=0,k;
	if (p==0) n=1;
 	while (contor < p)
    {
		n+=25;contor+=4;
		k=n;
		while (k%5==0) 
		{contor++;k/=5;}
	}
	if (contor>p) n-=(contor-p-1)*5;
	ofstream output("factorial.out");
	output<<n<<endl;
	output.close();
	return 0;
}