911 B | 911 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
BLANK = " "
inp = input
# inp = lambda : sys.stdin.readline()[:-1].strip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n = ii()
l = sorted([mii() + [_] for _ in range(n)], key=lambda t:(t[0], -t[1]))
chk1 = [False] * n
chk2 = [False] * n
mn = 1111111111111111
for i in range(n):
if mn > l[i][1]:
chk1[l[i][2]] = True
mn = min(mn, l[i][1])
l.sort(key=lambda t:(t[1], t[0]))
mn = 1111111111111111
for i in range(n):
if mn > l[i][0]:
chk2[l[i][2]] = True
mn = min(mn, l[i][0])
cnt = 0
for i in range(n):
if chk1[i] and chk2[i]:
cnt += 1
p(cnt)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()