n=int(input())
s={}
ss=[]
for i in range(n):
	si=input().split()
	if si[0] in s:
		s[si[0]].append(si[1])
	else:
		ss.append(si[0])
		s[si[0]]=[si[1]]
ss.sort()
for i in ss:
	s[i].sort()
	for j in s[i]:
		print(i+" "+j)