Here is my solution in PHP

s); arr); arr); res);

   `$resCount = count($`res);
   $result = -1;
   if($resCount == 1)
   {
    $result = -1;
   }
   else if(`$resCount == $`arrSum)
   {
    $result = -1;
   }
   else if(`$arr == $`arrRev)
   {
     $result = -1;
   }
   else
   {
    $equal = 'yes';
    $oddPair = '';
    $min = 0;
    foreach (`$res as $`key => $value) {
          if($value%2 !==0)
          {
            $equal = 'no';
            `$oddPair = $`key;
            if(`$value <$`min)
            {
               `$min = $`value; 
                `$oddPair = $`key;
            }


          }
    }
    `$len = count($`arr);

    if ($equal == 'no') {

         $findIndex = '';
         for (`$i=0; $`i < `$len ; $`i++) { 
               if(`$arr[$`i] == $oddPair)
               {

                 `$string = implode('', $`arr);

                       `$part1 = substr($`string, 0,$i);
                       `$part2 = substr($`string,`$i+1,$`len-1);


                     `$str1 = $`part1.$part2;

                     `$str2 = strrev($`str1);

                     if(`$str1 === $`str2)
                     {

                        `$findIndex =$`i;
                        break;
                     }

               }


         }
         `$result = $`findIndex;
    }

   }
   return $result;