function solve(firstChar, secondChar){
  let start = Math.min(firstChar.charCodeAt(firstChar), secondChar.charCodeAt(secondChar));
  let end = Math.max(firstChar.charCodeAt(firstChar), secondChar.charCodeAt(secondChar));
  let char = ''
  let output = '';


 for(let i = start+1; i < end; i++){
   char = String.fromCharCode(i);
     output += char + ' ';
 }
 console.log(output);
}