#include<stdio.h>
#include<iostream.h>
int main(void){
 long n,p,i;
 FILE *in=fopen("fact.in","rt"),*out=fopen("fact.out","w+");
 fscanf(in,"%ld",&p);
 for(i=0;i<100000;i++)
  if(i/5==p){
   fprintf(out,"%ld",i);
   break;
  else fprintf(out,"-1");
  }
}