data = []
while True:
    try:
        n = input()
        d = {}
        while True:
            k,v = input().split(' ')
            if k in d.keys():
                d[k] += int(v)
            else:
                d[k] = int(v)
    except (EOFError, KeyboardInterrupt):
        break

for k,v in sorted(d.items(), key=lambda x:int(x[0])):
    print(k+' '+str(v))