n = gets.to_i
str = gets.chomp.split(" ").map{|i| i.to_i}
cnt = 0
frag = 0
sum = 0

(n-1).times do |i|
    diff = str[i+1]-str[i]
    if frag != 0 && diff == frag then
        cnt += 1
        sum += cnt
    elsif diff == 1 || diff == -1 then
        cnt = 1
        sum += cnt
        frag = diff
    else
        frag = 0
    end
end

puts sum