Pyhon3 代码
n = int(input())
data = [list(map(int,input().split())) for _ in range(n)]
data.sort()
count = 0
k = 0
while k < n:
while k < n-1 and data[k][1] >= data[k+1][0] :
# 对于最后一个区间,不需要判断它和下一个区间是否可以合并,所以是k<n-1
k += 1
data[k][1] = max(data[k][1],data[k-1][1])
count += 1
k += 1
print(count)