The execution time is almost the same as ex3.
But, in this case, after increasing number of threads
4->10 and 10->100, the execution time sometimes
insignificantly increased (it happened before
several times). It is probably caused by
mutexes, since they don't allow multiple threads run
the locked code at the same time. The number of
threads is way higher than the number of physical
cores and the most of them don't even work at the same
time because of mutexes. The increased amount of
execution time is probably caused by the overheads of
threads and mutexes.