#include<stdio.h>    
int main()    
{    
unsigned long  p=0, p5=0, n=0, n5;    
FILE *f;    
f=fopen("fact.in", "r");    
fscanf(f,"%ul",&p);    
fclose(f);    
while(p5<p)    
{    
n+=5;    
n5=n;    
while(n5%5==0)   
{    
p5++;    
n5/=5;    
}    
}    
n=(p?n:1);    
f=fopen("fact.out","w");    
if (p5==p) fprintf(f,"%ul\n",n);    
else fprintf(f,"-1\n");    
fclose(f);    
return 0; }