题解 | 校门外的树
校门外的树
https://www.nowcoder.com/practice/0e8cfc82936048769af45967f3c4ef7e
L, M = map(int,input().split())
tree = [True] * (L+1)
for i in range(M):
li, ri = map(int,input().split())
for x in range(li,ri+1):
tree[x] = False
remaining_trees = sum(tree)
print(remaining_trees)
