Multiple if Statements?

So I'm trying to make a simple calculator, just to see if I can:

Java Code:

import java.util.Scanner;

class Calculator {

        public static void main(String[] args) {
                Scanner calculator = new Scanner(System.in);
                
                System.out.println("Hello, and welcome to Calculator.");
                System.out.println("Please type M for multiplication, D for division, S for addition, or A for subtraction.");
                String firstAnswer = calculator.nextLine();
                
                if (firstAnswer.equals("M")) {
                        System.out.println("You have selected multiplication. Please type the first number you wish to multiply.");
                        
                        double multiplyOne = calculator.nextDouble();
                        System.out.println("Please enter your second number.");
                        double multiplyTwo = calculator.nextDouble();
                        double multiplyResult = multiplyOne * multiplyTwo;
                        System.out.print("Your result is ");
                        System.out.print(multiplyResult);
                        
                        calculator.close();
                        System.exit(0);
        } if (firstAnswer.equals("D")); {
                        System.out.println("You have selected division. Please type the first number you wish to divide.");
                        
                        double divideOne = calculator.nextDouble();
                        System.out.println("Please enter your second number.");
                        double divideTwo = calculator.nextDouble();
                        double divideResult = divideOne / divideTwo;
                        System.out.print("Your result is ");
                        System.out.print(divideResult);
                        
                        calculator.close();
                        System.exit(0);
                        
        } if (firstAnswer.equals("A")); {
                        System.out.println("You have selected addition. Please type the first number you wish to add.");
                        
                        double addOne = calculator.nextDouble();
                        System.out.println("Please enter your second number.");
                        double addTwo = calculator.nextDouble();
                        double addResult = addOne + addTwo;
                        System.out.print("Your result is ");
                        System.out.print(addResult);
                        
                        calculator.close();
                        System.exit(0);

        } if (firstAnswer.equals("S")); {
                System.out.println("You have selected subtraction. Please type the first number you wish to subtract.");
                
                double subtractOne = calculator.nextDouble();
                System.out.println("Please enter your second number.");
                double subtractTwo = calculator.nextDouble();
                double subtractResult = subtractOne - subtractTwo;
                System.out.print("Your result is ");
                System.out.print(subtractResult);
                
                calculator.close();
                System.exit(0);
                
        } 
        
        }

}

(I'm probably doing something really stupid) Anyway, for some reason whenever I type anything other than M, it still sends me to division, even though there's no else. What am I doing wrong here?