#include <stdio.h>

int main() {
FILE * fin = fopen("fact.in","r");
FILE * fout = fopen("fact.out","w");
long long nr,pow,x,n,p;

 fscanf(fin,"%lld",&p);
 if (p==0) { fprintf(fout,"%lld\n",1); return 0; }
 nr=1; x=10;
 while (nr<p){
  nr=0; pow=5;
  while (x/pow>0) { nr+=x/pow; pow*=5; }
  n=x; x+=5;
 }
 if (nr==p) { fprintf(fout,"%lld\n",n); return 0; }
 fprintf(fout,"%d",-1);
 fclose(fin);  fclose(fout);
 return 0;
}