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

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, K;
    cin >> N >> K;
    vector<int> H(N);
    for (int i = 0; i < N; i++) cin >> H[i];

    deque<int> dq;

    for (int i = 1; i <= K && i < N; i++) {
        while (!dq.empty() && H[dq.back()] <= H[i])
            dq.pop_back();
        dq.push_back(i);
    }

    for (int i = 0; i < N; i++) {
        if (dq.empty() || H[dq.front()] <= H[i]) {
            cout << i + 1;
            return 0;
        }

        if (!dq.empty() && dq.front() == i + 1)
            dq.pop_front();

        int next = i + K + 1;
        if (next < N) {
            while (!dq.empty() && H[dq.back()] <= H[next])
                dq.pop_back();
            dq.push_back(next);
        }
    }

    cout << -1;
    return 0;
}