#include<fstream.h>
unsigned long int p,i,j,x;
int main()
{ifstream f("fact.in");
ofstream g("fact.out");
f>>p;
while((i+j)!=p)
	{i++;
	x=i;
	while(x%5==0)
		{j++;
		x=x/5;
		}
		if((i+j)>p)
			{g<<"-1";break;}
		if((i+j)==p)
			g<<i*5;
	}
f.close();
g.close();
return 0;
}