sadness

class Solution {
public:
    int countElements(vector<int>& a) {
        int ans = 0, n = a.size();
        for(int i = 0; i < n; i++){
            for(int j = 0; j < n; j++){
                if(a[j] == a[i]+1){
                    ans++;
                    break;
                }
            }
        }
        return ans;
    }
};