#include <iostream>

using namespace std;

int boldog(int a[200001], int n, int k){
    for(int i = 0; i < n; i++){
        bool b = true;
        int j = 0;
        while(j < k+1 && a[i] >= a[i+j]){
            j++;
        }
        if(j == k+1){
            return i+1;
        }
        else{
            i += j-1;
        }
    }

    return -1;
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int a[200001] = {0}, n, k;
    cin >> n >> k;

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

    cout << boldog(a, n, k);


    return 0;
}