2. Add and Remove Elements from Array

function solve(arr) {
    let modified = []
    let counter = 1;
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] === 'add') {
            modified.push(counter++)

        } else if (arr[i] === 'remove') {
            modified.pop(counter++)
        }

    }

    if (modified[0] === undefined) {
        console.log('Empty')
    } else {
        console.log(modified.join(' '));
    }

}