n = int(input())
l = []
ll = set()
for i in range(n):
s = input()
s = list(map(int,s.split()))
k = int(s[0])
ll.add(k)
t = (k,int(s[1]))
l.append(t)
for k in sorted(ll):
v = 0
for t in l:
if t[0]==k:
v += t[1]
print(k,v)