main (1) (1).cpp

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#include<iostream>
#include<unordered_set>
using namespace std;

unordered_set<int> s;

int main()
{
    int n, k, val;
    cin >> n >> k;
    for (int i = 0; i < n; i++)
    {
        cin >> val;
        s.insert(val);
    }
    int ans = 0;
    for (unordered_set<int>::iterator it = s.begin(); it != s.end(); ++it)
        if (s.find(*it + k) != s.end()) ans++;
    cout << ans << endl;
    return 0;
}