function arrayManipulator(numbers, commands) {

    for (let i = 0; i < commands.length; i++) {
        let command = commands[i].split(" ");
      switch (command[0]) {
        case "add":
          let addIndex = Number(command[1]);
          let elementToAdd = Number(command[2]);
          numbers.splice(addIndex, 0, elementToAdd);
          break;
        case "addMany":
          let addManyIndex = Number(command[1]);
          command.splice(0, 2);
          let numbersToAdd = command.map(Number);
          numbers.splice(addManyIndex, 0, ...numbersToAdd);
          break;
        case "contains":
          let checkElement = Number(command[1]);
            if (numbers.includes(checkElement)) {
              console.log(numbers.indexOf(checkElement));
              break;
            } else {
              console.log(-1);
              break;
            }
          break;
        case "remove":
          let removeIndex = Number(command[1]);
          numbers.splice(removeIndex, 1);
          break;
        case "shift":
          let shiftPositions = Number(command[1]);
          for (let l = 0; l < shiftPositions; l++) {
            let shiftetElement = numbers.shift();
            numbers.push(shiftetElement);
          }
          break;
        case "sumPairs":
          if (numbers.length % 2 !== 0) {
            numbers.push(0);
          }
          let sumArray = [];
          for (let m = 0; m < numbers.length; m += 2) {

            let sumPair = Number(numbers[i]) + Number(numbers[i + 1]);
            sumArray.push(sumPair);
        }
        numbers = sumArray;
          break;
        default:
          break;
      }
  }
  console.log('[ ' + numbers.join(', ') + ' ]');
}