#include<fstream.h>
#define input "fact.in"
#define output "fact.out"

int main()
	{
	int n,k,i,h;
	ifstream fin(input);
	ofstream fout(output);
	fin>>n;
	k=0;
	for(i=5;k<n;i=i+5)
		{
		k++;
      h=i/5;
		while(h%5==0)
			{
			k++;
			h=h/5;
			}
		}
	fout<<i-5;
	return 0;
	}