#include<stdio.h>
FILE *f=fopen("fact.in","r");
FILE *g=fopen("fact.out","w");

long long a,b,p,nr,x;

void solve()
{
 nr=0;
  if(p==0)
    fprintf(g,"1");
  else { a=1;
	  int k;
	  k=1;


	 while(nr<p)
	    {k=0;
		x=a;
		while(x%5==0)
                  {++k;x/=5;}
                
		  nr+=k+1;
                      	     
                ++a; }

	 if(nr==p)
	  fprintf(g,"%lld",(a-1)*5);
          else fprintf(g,"-1");
          }

	 
    

}


int main()
{

fscanf(f,"%lld",&p);
solve();
fcloseall();

return 0;
}