#include <stdio.h>
#include <stdlib.h>

int main()
{
    FILE *fin, *fout;
    fin=fopen("factorial.in", "r");
    fout=fopen("factorial.out", "w");
    int p, cp;
    long long n, cn;
    fscanf(fin, "%d", &p);
    n=0; cp=p;
    while(p>0){
      n+=5;
      cn=n;
      while(cn%5==0 && cn>0){
        p--;
        cn/=5;
      }
    }
    if(cp==0){
      fprintf(fout, "%d", 1);
    }
    else{
      if(p==0){
        fprintf(fout, "%d", n);
      }
      else{
        fprintf(fout, "%d", -1);
      }
    }
    fclose(fin);
    fclose(fout);
    return 0;
}