import java.util.Scanner;

public class Example { //931A

    public static void main(String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int a = sc.nextInt();

		int b = sc.nextInt();
		int total = 0;
		
		if (a >= 1 && a <= 1000 && b <= 1000 && b >= 1 ) {
			
			if((a - b) >= 0 && ((a - b) % 2) == 0) {
				for (int i = 0; i <= (a-b)/2; i++) 
					total = (total + i)*2;
				
				System.out.println(total);				
			}
			
			else if ((a - b) >= 0 && ((a - b) % 2 ) != 0) {
				for (int i = 0; i <= (a-b)/2; i++) 
					total = (total + i)*2;
				
				System.out.println(total+1);				
			}
			
			else if((a - b) <= 0 && ((b - a) % 2) == 0) {
				for (int i = 0; i <= (b - a)/2; i++) 
						total = (total + i)*2;
				
					System.out.println(total);					
			}
			
			else if ((a - b) <= 0 && ((b - a) % 2 ) != 0) {
				for (int i = 0; i <= (b - a)/2; i++) 
						total = (total + i)*2;
				
					System.out.println(total+1);		
			}
		}
	}
}

