#include <iostream>
#include<fstream>
using namespace std;
ifstream f("fact.in");
ofstream g("fact.out");
int countTrailingZeroes(unsigned int number)
{
	if (number < 5)
		      return 0;
	unsigned int numberfive = 0;
	for (unsigned int i = 1; i <= number; i++)
	{
		unsigned int element = i;
		while (element % 5 == 0)
		{
			numberfive++;
			element /= 5;
		}
	}
	return numberfive;
}
int main()
{

    /*int n;
cin>>n;
cout<<countTrailingZeroes(n);

cout<<'\n';
*/
int i,j,p;
//for(int lo=1;lo<=100;lo++)

//{
    f>>p;i=5;int k=p;



while(p>0)
{
    j=i;
    while(j%5==0)
    {
        p--;
        j/=5;
    }
    i+=5;
}
//g<<lo<<' '<<(i-5)<<'\n';
g<<i-5;
   return 0;
}