X and Y are playing a game. There are eleven coins on the table and each player must pick up at least one coin but not more than five in a turn. The person picking up the last coin loses. X starts. How many should he pick up to start to ensure a win no matter what strategy Y employs?
Is there a mathematical approach?

X and Y are playing a game. There are eleven coins on the table and each player must pick up at least one coin but not more than five in a turn. The person picking up the last coin loses. X starts. How many should X pick up to start to ensure a win no matter what strategy Y employs?

Is there a mathematical approach?