#include <iostream>
#include <vector>

using namespace std;

int main() {
    int n, k;
    cin >> n >> k;
    vector<int> v(n);
    for (int i = 0;i<n;i++) {
        cin >> v[i];
    }
    int i=0,s=-1;
    while(i!=s && i<n) {
        s=i;
        for (int j = i + 1; j <= i + k; j++) {
            if (v[j] > v[i]) {
                s = j;
                break;
            }

        }
        if(s!=i)
        {
            i=s;
            s=-1;
        }
    }
    if(i>=n)
    {
        cout<<"-1";
    }
    else
    cout << i+1;

    return 0;
}