/**

  • @param words String
  • @return String

*/
var Solution = function(words){

var a=words.length
var b=parseInt(a/2)
var count=0
for(var i=0;i<b;i++)
{
    if(words[i]===words[a-1-i])
    {
        count=count+1
    }
}

if(count===b)
{
    return '???'
}else
{
    return '????'
}

}