# Maximum Non-overlapping Bridges

easy

1. You are given a number n, representing the number of bridges on a river. 2. You are given n pair of numbers, representing the north bank and south bank co-ordinates of each bridge. 3. You are required to print the count of maximum number of non-overlapping bridges.

## Constraints

0 <= n <= 20 0 <= n1n, n1s, n2n, n2s, .. <= 100

## Format

### Input

A number n .. n pair of number each on a separate line (and pair separated by space)

### Output

A number representing the count of maximum number of non-overlapping bridges.

## Example

Sample Input

10
10 20
2 7
8 15
17 3
21 40
50 4
41 57
60 80
80 90
1 30

### Sample Output

7

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