h1, m1, s1 = map(int, input().split(":"))
h2, m2, s2 = map(int, input().split(":"))

if h1 == h2 and m1 == m2 and s1 == s2 :
    print("24:00:00")
else :
    t1 = h1*3600 + m1*60 + s1
    t2 = h2*3600 + m2*60 + s2

    diff = t2 - t1 if t2 > t1 else t2 - t1 + 24 * 3600
    
    h = diff // 3600
    m = (diff % 3600) // 60
    s = diff % 60
    
    print(f"{h:02d}:{m:02d}:{s:02d}")