There are two players, each has 20 marbles in their bag. There are 5 rounds and who wins more rounds will win the game. In each round, each player will take out a number of marbles. They can take out 0 marbles for one round only when they still have marbles). The one who takes out more marble wins (can be a draw if marbles are equal) and the marbles which are taken out by both players will be discarded.
A player will know how many marbles that the other player takes out. If a player has no marble left, they will play the next rounds as if they take out 0 marbles.
What is the best strategy to play this game (in first round or any round, when winning or losing)?