Max Number of K-Sum Pairs

class Solution {
public:
    int maxOperations(vector<int>& nums, int k) {
        unordered_map<int,int> m;
        int c=0;
        for(int i=0;i<nums.size();i++)
        {
            if(m[nums[i]]>0)
            {
                c++;
                m[nums[i]]--;
            }
            else
            {
                m[k-nums[i]]++;
            }
        }
        return c;
    }
};