function trans(s, n){
        //write code here
    const arr = s.split(' ').map((item)=>{
    let word = item.split('');
    for(let i=0;i<word.length;i++){
        if(word[i].charCodeAt(0)<word[i].toLowerCase().charCodeAt(0)){
           word[i] = word[i].toLowerCase(); //大写转为小写
        }else{
            word[i] = word[i].toUpperCase();
        }
    }
    return word.join('');
})
    return arr.reverse().join(' ');
}

module.exports = {
    trans : trans
}