#include <stdio.h>


long n,p,q,s,s1;

int main()
{FILE *fin,*fout;

fin=fopen("fact.in","r");
fscanf(fin,"%d",&p);
fclose(fin);

q=5;s=6;n=0;
if (p<s) n=5*p;

while (n==0)
 {q=q*5;
  if (p==s-1) n=-1;
  s1=5*s+1;
  if (p<s1) if ((p+1)%s==0) n=-1;
		     else n=p/s*q+(p%s)*5;
  s=s1;
  }


fout=fopen("fact.out","w");
fprintf(fout,"%d",n);
fclose(fout);

return 0;
}