Issue with future f.get() in C++

I am playing with std::async(), I have following code:

#include <iostream>
#include <future>
#include <mutex>
#include <queue>

using namespace std;

std::mutex mu;

queue<int> q;

void shared_cout(int id)
{
    mu.lock();
        q.push(id*id);
    mu.unlock();
}

int main()
{
        std::future<void> f[100];
        int i =0;


       while(true)

          {
               f[i]= std::async(shared_cout, i);
               if(i==99) { 
            int k=0; 
            while(k<100){
                f[k].get(); 
                if(!q.empty()){
                    cout<<q.front()<<endl; 
                    q.pop();
                       }  // end of  inner if
                    k++;  
            }  // end of inner - while
            i=-1;
        } // end of if
               i++;
          }  // end of while

        return 0;
}

I am creating 100 std::async calls. The problem here is, If I do say, f[1].get, It is stopping other threads from writing their value to the queue. But how do I modify this so that f[X].get() will not block other async calls to get their values(f[X].get should get called independently instead of sequential manner)?

(Note: I don't want the order to be preserved. Instead f[X].get() should finish as soon as f[X] async call is done.)