n,m = gets.chomp.split.map{|str| str.to_i}
shuffles = gets.chomp.split.map{|str| str.to_i}
target = shuffles[m -1]
(m - 2).downto(0) {|idx|
    tmp = shuffles[idx]
    if target == 1
    	target = tmp
    else 
    	if tmp < target
			next
		elsif tmp > target
			target -= 1
		else
			target = 1
		end
	end
}
puts target