#include <bits/stdc++.h>
using namespace std;
 
int countPairs(int arr[], int n, int target) {
     int cnt=0;
    unordered_map<int,int> mp;
    for(int i=0;i<n;i++){
        int complement = target - arr[i];
        if(mp.find(complement)!=mp.end()){
            cnt+=mp[complement];
        }
        mp[arr[i]]++;
    }
    return cnt;
}
int main() {
	// your code goes here
	int arr[5] = {1, 5, 7, -1, 5};
	int target=6;
	cout<<countPairs(arr,5,target);
	return 0;
}

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