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

int main()
{
    int N, K;
    cin >> N >> K;
    vector <int> H(N+1);
    for (int i = 1; i <= N; i++) { cin >> H[i]; }

    int i = 1;
    bool talalt = true;
    while (i < N) {
        talalt = true;
        for (int j = i+1; j <= i+K && j <= N; j++) {
            if (H[j] > H[i]) {
                talalt = false;
                i = j;
                break;
            }
        }
        if (talalt) {
            for (int j = i-1; i >= i-K && j >= 1; j--) {
                if (H[j] > H[i]) {
                    talalt = false;
                    i = j;
                    break;
                }
            }
        }
        if (talalt) { cout << i; break; }
    }

    if (!talalt) {cout << -1; }

    return 0;
}