#include<iostream.h>
#include<fstream.h>

ifstream f("fact.in");
ofstream g("fact.out");

int main()
{
int p,ok=0,n,k=0,cp;
f>>p;

for(n=5;ok==0 && n>0;n=n+5)
{
	
cp=n;
while(cp%5==0)
	{
	k++; 
	cp=cp/5;
	}

if(k>=p)
ok=n;

}

if(k!=p) g<<-1;
else g<<ok;

f.close();
g.close();

return 0;
}