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Time Limit: 1.0 Seconds Memory Limit: 65536K

Total Runs: 1118 Accepted Runs: 396 Multiple test files

Give you some magic sticks. Each magic stick has two different numbers carved
on it, one on each end. If one stick (a) has a1,a2 (a1 < a2), and another
stick (b) has b1,b2 (b1 < b2), a2 ≤ b1, then the two sticks can be
connected into a new stick, with a1,b2 carved on its two ends.

What is the minimum number of sticks after the connection?

**Input**

The first line is a integer N (N ≤ 20000) indicating the number of given sticks. Each of the following N lines contains two integers p and q (0 ≤ p < q ≤ 10^{8}), denoting the two number carved on a stick.

**Output**

Output the minimum number of sticks after the connection.

**Sample Input**

4 1 5 3 8 5 21 13 34

**Sample Output**

2

Maintance:G.D.Retop. Developer: SuperHacker, G.D.Retop