#include<stdio.h> 
int main() 
{ 
unsigned int p=0, p5, i, z, n, k;
FILE *f; 
f=fopen("fact.in", "r"); 
fscanf(f,"%d",&p); 
fclose(f); 
z=p+1;
k=p+1;
while(z>p)
{
	k--;
	n=5*k;
	z=0;
	p5=1;
	i=1;
	while(i>=1){
		p5=p5*5;
		i=n/p5;
		z=z+i;
		}
}

 n=(p?n:1);
 f=fopen("fact.out","w"); 
 if (z==p)
 fprintf(f,"%d\n",n);
 else
 fprintf(f,"-1\n");
 fclose(f);
 return 0; }