function processData(input) {
    const undo = [""];
    const operations = [
        (append) => undo.push(undo.at(-1) + append),
        (_delete) => undo.push(undo.at(-1).slice(0, undo.at(-1).length - _delete)),
        (print) => console.log(undo.at(-1).at(print - 1)),
        () => undo.pop()
    ];
    input.split("\n").slice(1).forEach((operation) => operations[operation.split(" ")[0] - 1](operation.split(" ")[1]));
}