v = list()
i = 0
for i in range(10):
a = int(input())
b = int(input())
if ((a+b) % 2 == 0):
if (a % 2 == 0):
v.append((a/2) + (b/2))
v.append((a/2) - (b/2))
else:
v.append((a/2 + (b+1)/2))
v.append((a/2) - (b/2))
for i in range(20):
print(v[i])
diA9IGxpc3QoKQoKaSA9IDAKZm9yIGkgaW4gcmFuZ2UoMTApOgogICAgCiAgICBhID0gaW50KGlucHV0KCkpCiAgICBiID0gaW50KGlucHV0KCkpCiAgICBpZiAoKGErYikgJSAyID09IDApOgogICAgICAgIGlmIChhICUgMiA9PSAwKToKICAgICAgICAgICAgdi5hcHBlbmQoKGEvMikgKyAoYi8yKSkKICAgICAgICAgICAgdi5hcHBlbmQoKGEvMikgLSAoYi8yKSkKICAgICAgICBlbHNlOgogICAgICAgICAgICB2LmFwcGVuZCgoYS8yICsgKGIrMSkvMikpCiAgICAgICAgICAgIHYuYXBwZW5kKChhLzIpIC0gKGIvMikpCgpmb3IgaSBpbiByYW5nZSgyMCk6CiAgICBwcmludCh2W2ldKQo=