#include<fstream>
using namespace std;
int main()
{
	int p,l,i,v[721],u,j;
	ifstream cin("fact.in");
	ofstream cout("fact.out");
	cin>>p;
	i=1;
	l=0;
	if(p=0)
		cout<<1;
	else{
	for(j=5;j<=36000;j*=5)
	{
		++u;
		v[j]=u;
	}
	while(l<p)
	{
		if(i%5==0)
			for(j=5;j<=3600;j*=5)
				if(i==v[j])
					l+=v[j]-1;
			l++;
		++i;
	}
	cout<<i;
	}
	cin.close();
	cout.close();
	return 0;
}