Is it compulsory to enter Europe in the same country as the Schengen?
no it is not. it is however compulsory to enter Schengen Area with the same intended purpose as your visa application at least for the first time. e.g 1. you applied at the French embassy because your main intended purpose is to tour France. However, from your country, the most direct flight is flying to Amsterdam first. Therefore you are allowed to enter Schengen Area via Netherlands with your onward journey to France. e.g. 1 : it is ok to enter Schengen Area from a different country of your application. e.g. 2 you applied at the French embassy because you were able to get an earlier appointment even though your planned travel has more time spent at Germany. You flew to Germany for your travel. e.g. 2 it is not ok! you will be deported. e.g.3 you were issued 3 year validity visa by the French Embassy, and you used it first time for the intended purpose (i.e. travel to France). Your 2nd visit later, you flew to Italy for another purpose with the same valid visa. e.g. 3 it is ok!