class Storage {

        constructor (capacity) {

          let arr = [];

          let cost = 0;



         this.addProduct = function (obj) {

          arr.push(JSON.stringify(obj));

          capacity -= obj.quantity;

          cost += obj.price * obj.quantity;

         this.capacity = capacity;

         this.totalCost = cost;

         }



         this.getProducts = function () {

          return arr.join('\n');

         }

        }

      }