C++ :

#include <iostream>
#include <cmath>
#include <cstring>
using namespace std;
char c1,c2;
int main()
{
  cin>>c1>>c2;
  for (char c=c1;c<=c2;c+=2) cout<<c<<" ";
  cout<<endl;
  for (char c=c2;c>=c1;c-=2) cout<<c<<" ";
  cout<<endl;
  return 0;
}