- 우선순위 큐를 활용한 최소 회의실 개수 문제다.
import heapq
import sys
input = sys.stdin.readline
N = int(input())
timetable = []
heap = []
for _ in range(N):
S, T = map(int, input().strip().split())
timetable.append([S, T])
timetable.sort(key=lambda x : x[0])
heapq.heappush(heap, timetable[0][1])
for i in range(1, N):
if heap[0] > timetable[i][0]:
heapq.heappush(heap, timetable[i][1])
else:
heapq.heappop(heap)
heapq.heappush(heap, timetable[i][1])
print(len(heap))