class Solution {

public:

vector<int> findNumsAppearOnce(vector<int>& nums) {

    vector<int> b;

    std::sort(nums.begin(),nums.end());

    for(int i=0;i<nums.size(); ){

        if(nums[i]==nums[i+1])

            i=i+2;

        if (nums[i]!=nums[i+1]){

            b.push_back(nums[i]);

            i+=1;

        if(b.size()==2)return b;

        }
    }
}

};