#include<fstream>
#define MAXN 20000000

using namespace std;

ifstream in("factorial.in");
ofstream out("factorial.out");

int v[MAXN];

int main()
{
	int n;
	in>>n;
	for(int i=5;;i+=5)
	{
		int j=i;
		v[i/5]=v[i/5-1]+1;
		j=j/5;
		while(j%5==0)
		{
			v[i/5]++;
			j=j/5;
		}
			if(v[i/5]==n)
			{
				out<<i;
				return 0;
			}			
	}
	return 0;
}