a = float(input())

if a < 0:
    print('Err')
elif a > 0:
    x1 = -1 * a
    x2 = a
    print('x ∈ (-∞ ; ', x1, ') ⋃ (, x2, ; +∞)')
else:
    print('x ∈ (-∞ ; 0) ⋃ (0; +∞)')