(by using threads)

Modify the following code to demonstrate context switching between parallel running threads. The program must fulfil the following requirements: There should be 4 threads created using Pthreads API. While all/any the threads are running, the main() function should be waiting for the threads to finish their execution. The 1st thread should continuously print the character "1" in a loop. the 2nd thread should continuously print the character "2" in a loop. the 3rd thread should continuously print the character "3" in a loop. The 4th thread should continuously check for keyboard input. As soon as the user presses the Q key, the program should terminate. Right before termination, the main() function displays the number of i's, 2's, and 3's printed out by each thread. NNN NNN NNN NNN NN NN NN Nw Nw N Sample Output 11111111 11122222222222111 22222333 111111222222222 222222222 3333333333333133333 3333332 22222222 3333222 2233333333333333333 2222222223 Number of ls - 141 Number of 2s - 121 Number of 39 - 98 12222222222 1222222 1111333 333333333 33333333222 - S