hash_tab = {}
while True:
    try:
        num_list = input().split(' ')
    except:
        break
    if len(num_list) == 1:
        ...
    else:
        key = int(num_list[0])
        value = int(num_list[1])
        if hash_tab.get(key):
            hash_tab[key] += value
        else:
            hash_tab[key] = value
keys = sorted(hash_tab)    # 注意题目描述,升序排列键值
for key in keys:
    print(key, hash_tab[key])