A, B = input().split()
A = int(A)
B = int(B)
add = A + B

if add % 2 == 0:
	result = int(add / 2)
	print(result)
	abs_result = abs(A - result)
	print('|{}-{}| = {} and |{}-{}| = {}, so {} satisfies the condition.'.format(A, result, abs_result, B, result, abs_result, result))
else:
	print('IMPOSSIBLE')
	print('No integer satiesfies the condition.')