java 代码
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int b = scanner.nextInt();
int c = scanner.nextInt();
int d = scanner.nextInt();
int x = a * b - c * d;
System.out.println("DIFERENCA = " + x);
}
}