The rule is easy.
Three coins are here.
Player 1 decides the number of coins concealed in the palm.
Player 2 forecasts the number of coins that exist in the palm of player 1.
When player 2 is a correct answer, it is score of player 2(It is 300 points or 500 points).
If player 2 makes a mistake in it, it is a score of player 1(300 points).
The player reasons getting a hint from the expression and the speech and behavior of the history,
the score situation, and the other party of the number of coins.
This game is "Psychology game" that forecasts the number of coins.
It is alias "The oldest game in the human race. "