#include <iostream>
#include <vector>

using namespace std;

int main()
{
    int n, k;

    cin >> n >> k;
    vector<int> mfa(n);
    for (int i = 0; i < n; i++)
    {
        cin >> mfa[i];
    }

    int i=0, vege, j;
    while (i<n)
    {
        vege= (n < i+k+1 ? n : i+k+1);
        j=i+1;
        while (j < vege && mfa[i] >= mfa[j])
        {
            j++;
        }
        if (j == vege)
        {
            cout << i+1;
            return 0;
        }
        else
        {
            i = j;
        }
    }
    cout << -1;
    return 0;
}