"""
출처:프로그래머스,
https://school.programmers.co.kr/learn/courses/30/lessons/181188
"""

# 풀이 과정
def solution(targets):
    targets.sort(key=lambda x: x[1])
    target = 0
    count = 0
    for x, y in targets:
        if target <= x:
            count += 1
            target = y

    return count