require 'Monitor'
lock = Monitor.new
count = 0;
t1 = Thread.new do
　100000.times do
　　lock.synchronize do
　　　count += 1
　　end
　end
end
t2 = Thread.new do
　100000.times do
　　lock.synchronize do
　　　count += 1
　　end
　 end
end
t1.join; t2.join
puts count