// Source: https://usaco.guide/general/io

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

int main() {
	int n, k;
	cin>>n>>k;
	vector<int>m(n);
	for (int i=0;i<n;i++) {
		cin>>m[i];
	}
	int most=m[0];
	int ind=0;
	bool lat = true;
	while (lat == true) {
		lat = false;
		for(int i=ind;i<ind + k+1;i++){
			if (m[i]>most) {
				most= m[i];
				lat = true;
				ind = i;
			}
		}		
	}
	if (most == m[0]) {
		cout<<"-1";
		return 0;
	}
	if(lat == false){
		cout<<ind+1;
	}
}