#include <iostream>
#include <vector>
#include <unordered_map>
#include <cassert>

int unique_sum(const std::vector<int>& nums) {
  std::unordered_map<int, int> hashMap;
  for (int i = 0; i < nums.size(); i++) {
    if (hashMap.find(nums[i]) == hashMap.end()) {
      hashMap[nums[i]] = nums[i];
    } else {
      hashMap[nums[i]] = 0;
    }
  }
  int sum = 0;
  for (auto i: hashMap) {
    sum = sum + hashMap[i.first];
  }
  return sum;
}