#include <string> 
#include <thread> 
#include <vector> 
#include <iostream> 
#include <atomic> 
#include <numeric> 
  
const int N = 10000; 
std::atomic<int> cnt; 
std::vector<int> data(N); 
  
void reader(int id) { 
         for (;;) { 
               int idx = atomic_fetch_sub_explicit(&cnt, 1, std::memory_order_relaxed); 
               if (idx >= 0) { 
                           std::cout << "reader " << std::to_string(id) << " processed item " 
                                       << std::to_string(data[idx]) << '\n'; 
               }  
         else { 
                           std::cout << "reader " << std::to_string(id) << " done.\n"; 
                           break; 
               } 
         } 
} 
  
int main() { 
         std::iota(data.begin(), data.end(), 1); 
         cnt = data.size() - 1; 
  
         std::vector<std::thread> v; 
         for (int n = 0; n < 10; ++n) { 
               v.emplace_back(reader, n); 
         } 
 
         for (std::thread& t : v) { 
               t.join(); 
         } 
}