function processData(input) {
  // Define a queue
  class Fifo {
    constructor() {
      this.stackEnqueue = [];
      this.stackDequeue = [];
    }

    enqueue(x) {
      this.stackEnqueue.push(x);
    }

    transfer() {
      while (this.stackEnqueue.length > 0) {
        this.stackDequeue.push(this.stackEnqueue.pop());
      }
    }
    dequeue() {
      if (this.stackDequeue.length === 0) {
        this.transfer();
      }
      this.stackDequeue.pop();
    }
    peek() {
      if (this.stackDequeue.length === 0) {
        this.transfer();
      }
      if (this.stackDequeue.length === 0) {
        return null;
      } else {
        return this.stackDequeue[this.stackDequeue.length - 1];
      }
    }
  }

  let q = new Fifo();

  // Parse input

  const inputs = input.split('\n');

  for (let i = 1; i <= Number(inputs[0]); i++) {
    const element = inputs[i];
    const inputArray = element.split(' ');

    const action = Number(inputArray.shift());
    const value = Number(inputArray.join(''));

    switch (action) {
      case 1:
        q.enqueue(value);
        break;

      case 2:
        q.dequeue();
        break;

      case 3:
        console.log(q.peek());
        break;

      default:
        console.log('DEFAULT REACHED');
        console.log('Unexpected action', action, 'With Value', value);

        break;
    }
  }
}