a=int(input())
b=int(input())
c=(a+b)//2
d=0
g=0
e=1
f=1
if (a-b==1)or(b-a==1):
    print(1)
else :
    if (a<b):
        for i in range (a,c):
            d=d+e
            e=e+1
        for j in range (c,b):
            g=g+f
            f=f+1
        print(d+g)
    else :
         for i in range (b,c):
            d=d+e
            e=e+1
         for j in range (c,a):
            g=g+f
            f=f+1
         print(d+g)
        
