var LFUCache = function(capacity) {
  this.storage = {};
  this.capacity = capacity;
  this.keys = [];
};

LFUCache.prototype.get = function(key) {
  var index = this.keys.indexOf(key);
  if (index > 0) {
    this.keys.splice(index, 1);
    this.keys.unshift(key);
  }
  return this.storage[key] ? this.storage[key] : -1
};

LFUCache.prototype.put = function(key, value) {
  var cacheCurrentLength = Object.keys(this.storage).length;
  if (cacheCurrentLength < this.capacity) {
    this.keys.unshift(key);
    this.storage[key] = value;
  } else {
    var LFUKey = this.keys.pop();
    delete this.storage[LFUKey];
    this.keys.unshift(key);
    this.storage[key] = value;
  }
};