#include <thread>
#include <mutex>
#include <iostream>
#include <chrono>
std::mutex m1,m2;
void foo() {
  m1.lock();
  std::cout<<"foo locked m1"<<std::endl;
  std::this_thread::sleep_for (std::chrono::seconds(1));
  m2.lock();
  m1.unlock(); 
  std::cout<<"foo locked m2 and releases m1"<<std::endl;
  m2.unlock(); 
  std::cout<<"foo is ok"<<std::endl;
}
void bar() {
  m2.lock();
  std::cout<<"bar locked m2"<<std::endl;
  std::this_thread::sleep_for (std::chrono::seconds(1));
  m1.lock();
  m2.unlock(); 
  std::cout<<"barlocked m1 and releases m2"<<std::endl;
  m1.unlock(); 
  std::cout<<"bar is ok"<<std::endl;
}
int main()
{
   std::thread t1(foo); 
   bar(); 
   t1.join(); 
   std::cout << "Everything went fine"<<std::endl; 
   return 0;  
}

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