import sys
n = int(sys.stdin.readline())
l = [[*map(int, sys.stdin.readline().split())] for i in range(n)]
mx = {}
cnt = {}
for c, info in l:
_mx = mx.get(info, -1)
if _mx < c:
mx[info] = c
cnt[info] = 1
elif _mx == c:
cnt[info] = cnt.get(info, 0) + 1
print(len(cnt))
# print(sum(cnt.values()))