import java.math.BigInteger;

class Grains {

    BigInteger grainsOnSquare(final int square) {

        if (square < 1 || square > 64){
            throw new IllegalArgumentException("square must be between 1 and 64");
        }
        return BigInteger.TWO.pow(square - 1);
    }

    BigInteger grainsOnBoard() {

        BigInteger grainsOnBoard = BigInteger.ZERO;
        
        for (int i = 1; i <= 64; i++){
            grainsOnBoard = grainsOnBoard.add(grainsOnSquare(i));
        }
        return grainsOnBoard;
    }
}