fhs

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

int main() {
int N, C;
cin >> N >> C;
unordered_map<int, int> freq;
long long count = 0;

for (int i = 0; i < N; ++i) {
    int num;
    cin >> num;
    count += freq[num - C];
    freq[num]++;
}

cout << count << endl;
return 0;

}