1608. Special Array With X Elements Greater Than or Equal X

class Solution {
public:
    int specialArray(vector<int>& nums) {
        sort(nums.begin(),nums.end());
        for(int i=1;i<=nums.size();i++){
            auto it=lower_bound(nums.begin(),nums.end(),i);
            if(nums.end()-it==i) return i;
        }
        return -1;
    }
};