Test

l = sorted([120,250,145,40,230,20])
count = 0
for i in l:
    if count < 0:
        print(str(i) + " - " + str(l[count+1]))
    elif count > len(l):
        print(str(i) + " - " + str(l[count-1]))   
    else:
        if i - l[count-1] > i - l[count+1]:
            print(str(i) + " - " + str(l[count-1]))
        else:
            print(str(i) + " - " + str(l[count+1]))
    count += 1