T = gets.to_i

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

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

  vs = counter.values

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