Sigma

#include <bits/stdc++.h>
#define ll long long
using namespace std;

const int oo = 1e9 + 7;
const int N = 1e3 + 5;

int n, k;
int a[N];

int main() {
    cin >> n >> k;
    int maxx = 0, minn = oo;
    for (int i = 1; i <= n; ++i) {
        cin >> a[i];
        maxx = max(maxx, a[i]);
        minn = min(minn, a[i]);
    }

    sort(a + 1, a + n + 1);

    int ans = 0;
    int X = (maxx - minn) / (k - 1);
    for (int d = 1; d <= X; ++d) {
        for (int i = 1; i <= n; ++i) {
            for (int j = i; j <= n; ++j) {
                if (a[j] - a[i] == d) {
                    ans += (n - 2);
                    cout << i << ' ' << j << '\n';
                    break;
                }
            }
        }
    }

    cout << ans;

    return 0;

}