function solve(input = []){

    let library = input.shift().split(`&`);

    for(let i = 0; i < input.length; i++){

        let tokens = input[i].split(` | `);

        let command = tokens[0];
        let firstBook = tokens[1];
        let secondBook = tokens[2];

        if(command === `Add Book`){
            if(!library.includes(firstBook)){
                library.unshift(firstBook);
            }
        }
        else if(command === `Take Book`){
            if(library.includes(firstBook)){
                let indexOfTheBook = library.indexOf(firstBook);
                library.splice(indexOfTheBook,1);
            }
        }
        else if(command === `Swap Books`){
            if(library.includes(firstBook, secondBook)){
                let indexOfTheBook = library.indexOf(firstBook);
                let indexOfTheSecondBook = library.indexOf(secondBook);


                library[indexOfTheBook] = secondBook;
                library[indexOfTheSecondBook] = firstBook;
            }
        }
        else if(command === `Insert Book`){
            library.push(firstBook);
        }
        else if(command === `Check Book`){
            let searchIndex = firstBook;

            if(searchIndex > 0 && searchIndex < library.length){
                console.log(library[i]);
            }
        }
        else if(command === `Done`){
            console.log(`${library.join(`, `)}`);
        }
    }
}

solve([`Don Quixote&The Great Gatsby&Moby Dick&Hamlet`,
`Add Book | The Odyssey`,
`Take Book | Don Quixote`,
`Insert Book | Alice's Adventures in Wonderland`,
`Check Book | 3`,
`Done`
])


solve([`Anna Karenina&Heart of Darkness&Catch-22& The Stranger`,
`Add Book | David Copperfield`,
`Add Book | One Thousand and One Nights`,
`Swap Books | One Thousand and One Nights | Catch-22`,
`Take Book | David Copperfield`,
`Insert Book | The Stories of Anton Chekhov`,
`Check Book | 17`,
`Done`
])