# input
import sys
input = sys.stdin.readline
II = lambda : int(input())
MI = lambda : map(int, input().split())
LI = lambda : [int(a) for a in input().split()]
SI = lambda : input().rstrip()
LLI = lambda n : [[int(a) for a in input().split()] for _ in range(n)]
LSI = lambda n : [input().rstrip() for _ in range(n)]
MI_1 = lambda : map(lambda x:int(x)-1, input().split())
LI_1 = lambda : [int(a)-1 for a in input().split()]

mod = 998244353
inf = 1001001001001001001
ordalp = lambda s : ord(s)-65 if s.isupper() else ord(s)-97
ordallalp = lambda s : ord(s)-39 if s.isupper() else ord(s)-97
yes = lambda : print("Yes")
no = lambda : print("No")
yn = lambda flag : print("Yes" if flag else "No")

prinf = lambda ans : print(ans if ans < 1000001001001001001 else -1)
alplow = "abcdefghijklmnopqrstuvwxyz"
alpup = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
alpall = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
URDL = {'U':(-1,0), 'R':(0,1), 'D':(1,0), 'L':(0,-1)}
DIR_4 = [[-1,0],[0,1],[1,0],[0,-1]]
DIR_8 = [[-1,0],[-1,1],[0,1],[1,1],[1,0],[1,-1],[0,-1],[-1,-1]]
DIR_BISHOP = [[-1,1],[1,1],[1,-1],[-1,-1]]
prime60 = [2,3,5,7,11,13,17,19,23,29,31,37,41,43,47,53,59]
sys.set_int_max_str_digits(0)
# sys.setrecursionlimit(10**6)
# import pypyjit
# pypyjit.set_param('max_unroll_recursion=-1')

from collections import defaultdict,deque
from heapq import heappop,heappush
from bisect import bisect_left,bisect_right
DD = defaultdict
BSL = bisect_left
BSR = bisect_right

"""
正直使い物になりませんね。
基本的にcppに書き直さなきゃいけなくなると思います。
(TLEによりverifyできませんでした)
"""

class BIT2D:
    __slots__ = ("h", "w", "data")
    def __init__(self, h, w):
        self.h = h
        self.w = w
        self.data = [dict() for i in range(h + 1)]
    
    def add(self, i, j, x):
        i += 1
        while i <= self.h:
            bit = self.data[i]
            k = j+1
            while k <= self.w:
                if not k in bit:
                    bit[k] = x
                else:
                    bit[k] += x
                k += k&-k
            i += i&-i
    
    def prod(self, i, j):
        res = 0
        while i > 0:
            if len(self.data[i]):
                bit = self.data[i]
                k = j
                while k > 0:
                    if k in bit:
                        res += bit[k]
                    k -= k&-k
            i -= i&-i
        return res
    
    def rectangle(self, l, d, r, u):
        res = self.prod(r, u) - self.prod(r, d)
        return res

lim = 10 ** 6
n = II()
bit = BIT2D(lim, lim)
ans = 0
for i in range(n):
    l, r = MI()
    ans += bit.prod(l, lim - r)
    bit.add(l, lim - r, 1)
print(ans)