A festival lists n events. Event i is available on every day in the inclusive range [s[i], e[i]] (days are integers, s[i] ≤ e[i]). You may attend at most one event per day, and each event may be attended on at most one day chosen from within its own range. Different events attended on different days may have overlapping ranges — only the actual chosen days must be distinct.

Maximize the number of events you attend, and output that maximum count.

Input format

Line 1: an integer n. Next n lines: two integers s and e — the first and last available day of one event.

Output format

A single integer: the maximum number of events that can be attended.

Constraints

• 1 ≤ n ≤ 100000
• 1 ≤ s[i] ≤ e[i] ≤ 1000000000

3
1 2
2 3
3 3

3

2
1 1
1 1

1