T = gets.to_i

T.times do
  n, m = gets.split.map(&:to_i)
  counter = Array.new(n, 0)

  m.times do
    u, v = gets.split.map(&:to_i)
    counter[u - 1] += 1
    counter[v - 1] += 1
  end

  if counter.size != counter.uniq.size
    puts 'Yes'
  else
    puts 'No'
  end
end