#include <stdio.h>

int main()
{
freopen("fact.in", "r", stdin);
freopen("fact.out", "w", stdout);

long p,i,aux;

scanf("%ld",&p);
i=0;
if (p!=0){
while (p>0)
       {
       i+=5;
       aux=i;
       while (aux%5==0) {
			p--;
			aux=aux/5;
			}
       }
}
else i=1;
if (p<0) i=-1;
printf("%ld", i);
return 0;
}