n, s, t, k = gets.split.map(&:to_i)
a = gets.split.map(&:to_i)
s -= 1
t -= 1

if a[s] + a[t] <= k then
    puts 1
else
    # a[s] -> min(A) -> a[t]
    mn = 2_000_000_000
    (0..n - 1).each do |i|
        if i == s or i == t then
            next
        end
        if mn > a[i] then
            mn = a[i]
        end
    end
    if a[s] + mn <= k and mn + a[t] <= k then
        puts 2
    else
        puts -1
    end
end