1
a = int(input())
b = int(input("\n"))
out=0
for i in range(a, b):
out = out+ i
out -=a
print(out)
2
out +=b
1
a = int(input())
b = int(input("\n"))
out=0
for i in range(a, b):
out = out+ i
out -=a
print(out)
2
a = int(input())
b = int(input("\n"))
out=0
for i in range(a, b):
out = out+ i
out +=b
print(out)