n=int(input())
dt={}
for i in range(n):
    cc=input().split()
    dt[cc[1]]=dt.get(cc[1],0)+int(cc[0])
print(dt)

result = []
for x in dt.items():
    result.append(x) 
result.sort(key =lambda x:x[0])
for x in result:
    print(x[0],x[1])