#include <bits/stdc++.h>

#include <atcoder/fenwicktree.hpp>
#include <atcoder/segtree.hpp>
#include <atcoder/modint.hpp>
#include <atcoder/dsu.hpp>
#include <atcoder/lazysegtree.hpp>

using namespace atcoder;
using namespace std;
using ll = long long;
using ull = unsigned long long;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<>>;
ll ll_min = numeric_limits<ll>::min();
ll ll_max = numeric_limits<ll>::max();
ll ALPHABET_N = 26;
using mint = modint998244353;
#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define rep_(i, k, n) for (ll i = (ll)k; i < (ll)n; i++)
#define all(a) a.begin(), a.end()

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	ll n, s, t, k;
	cin >> n >> s >> t >> k;
	s--;
	t--;
	set<pair<ll, ll>> a_i;
	vector<ll> A(n);
	rep(i, n)
	{
		cin >> A[i];
		a_i.insert({A[i], i});
	}
	vector<ll> dist(n, ll_max);
	dist[s] = 0;
	queue<ll> q;
	q.push(s);
	a_i.erase({A[s], s});
	while (!q.empty())
	{
		ll v = q.front();
		q.pop();
		if (v == t)
		{
			cout << dist[v] << endl;
			return 0;
		}
		for (auto it = a_i.begin(); it != a_i.end();)
		{
			ll a = it->first;
			ll i = it->second;
			if (!(A[v] + a <= k))
			{
				break;
			}
			dist[i] = dist[v] + 1;
			q.push(i);
			it = a_i.erase(it);
		}
	}
	cout << (dist[t] == ll_max ? -1 : dist[t]) << endl;
	return 0;
}