bank = [0, 0, 0]
time = []
n = int(input())
for i in range(n):
    x, y = map(int, input().split())
    time.append(x * 60 + y)
for i in range(n):
    r = min(bank)
    ind = 0
    for j in range(3):
        if bank[j] == r:
            ind = j
    if bank[ind] > time[i]:
        x = bank[ind] + 30
        print(x // 60, x % 60)
    else:
        x = time[i] + 30
        print(x // 60, x % 60)
    bank[ind] = max(time[i], bank[ind]) + 30