int cntDisPairs(vector<int> arr, int target) {
unordered_set<int> set;
unordered_set<int> seen;
int count = 0;
for(int num : arr) {
if(set.find(target-num) != set.end() && seen.find(num) == seen.end() ) {
count++;
seen.insert(num);
seen.insert(target-num);
}
set.insert(num);
}
return count;
}