题解 | #小乐乐走台阶#

function show(n) {
  if (n == 1) {
    return 1;
  } else if (n == 2) {
    return 2;
  } else {
    return show(n - 1) + show(n - 2);
  }
}

let n = Number(readline());
console.info(show(n));