The simplest version of the clock paradox is the following: A and B are two adjacent atomic clocks at rest (v = 0) in a closed inertial system K. After an acceleration period, the atomic clock A travels with constant velocity va at L distance, then stops and moves contrariwise with constant velocity at L distance before slows it down and stops next to clock B. According to the standard theoretical statement, the clock in motion would run slower, therefore, after returning next to clock B, clock A shows less time elapsed as clock than clock B that remained at rest. This can be described with the frequency changes of the clocks. The frequency of the clock in motion is