n = int(input())
day = 24 * 60
times = []
for i in range(n):
    ex = list(map(int, input().replace(':', ' ').split()))
    #print(ex)
    times.append((ex[0] * 60 + ex[1] + ex[2]) % day)
    #print(times)
times.sort()
for i in times:
    hours =  str(i // 60)
    mins = str(i % 60)
    if len(hours) == 1:
        print('0' + hours, end=':')
    else:
        print(hours, end=':')
    if len(mins) == 1:
        print('0' + mins)
    else:
        print(mins)