题解 | #合并表记录#

n=int(input())
dict={}
for i in range(n):
    line=input().split()
    key=int(line[0])
    value=int(line[1])
    if key in dict.keys():
        dict[key]=int(dict[key])+int(value)
    else:
        dict[key]=value
for key,value in sorted(dict.items()):
    print(f'{key} {value}')