#include<fstream> 
using namespace std; 
ifstream f("fact.in"); 
ofstream g("fact.out"); 
long long pt; 
int n,p,u,m,k,nr; 
int main()
{    
	f>>k;  
	p=1;    
	u=2000000000;  
	if(k==0)    
	{         
		g<<1;    
		return 0;     
	}    
	while(p<=u){         
		m=(p+u)/2;        
		pt=5;
		nr=0;
		while(pt<=m)
		{             
			nr=nr+m/pt;           
			pt=pt*5;           
		}        
		if(nr==k)
		{         
			while(m%5!=0)         
				m--;           
			g<<m;         
			break;       
			}        
		else        
			if(nr<k)      
				p=m+1;     
			else         
				u=m-1;     
			}    
	if(p>u)      
		g<<-1;   
	return 0;   
}