#include<stdio.h>
long p;  
int main()  
 {  
long li,ls,i,s,num;  
freopen("fact.in","r",stdin);
freopen("fact.out","w",stdout);
scanf("%ld",&p);  
  if(p)  
  {  
li=p<<2;  
ls=p+(p<<2);  
for(i=li;i<=ls;++i)  
{
s=0;
num=5;
while(i/num)
{
s+=i/num;
num=num+(num<<2);
}
if(s==p)
  {
  printf("%ld",i);  
  return 0;  
  }  
}
}
else
{
printf("1");
return 0;
}
printf("-1");
fcloseall();
return 0;
}