백준 1931번(python)

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N = int(input())

meeting_list = [list(map(int, input().split())) for _ in range(N)]
# 파이썬에서 여러 조건으로 정렬하는 방법
meeting_list = sorted(meeting_list, key = lambda x:(x[1], x[0]))

max_meeting = 0
start = 0

for time in meeting_list:
    if(time[0] >= start):
        start = time[1]
        max_meeting += 1
        
print(max_meeting)