Score : $400$ points

问题陈述

AtCoder 城市将举行市长选举。候选人是青木和高桥。 该城市由 $N$ 个城镇组成，第 $i$ 个城镇有 $A_i$ 名支持青木的选民和 $B_i$ 名支持高桥的选民。没有其他选民。 高桥可以在每个城镇发表演讲。 如果他在某个城镇发表演讲，那么该城镇的所有选民，无论是支持高桥还是青木，都会投票给高桥。 另一方面，如果他不在某个城镇发表演讲，那么该城镇支持青木的选民将投票给青木，而支持高桥的选民将不会投票。 为了获得比青木更多的选票，高桥至少需要在多少个城镇发表演讲？

以上为大语言模型 kimi 翻译，仅供参考。

Problem Statement

AtCoder City will hold a mayoral election. The candidates are Aoki and Takahashi.
The city consists of $N$ towns, the $i$-th of which has $A_i$ pro-Aoki voters and $B_i$ pro-Takahashi voters. There are no other voters.
Takahashi can make a speech in each town.
If he makes a speech in some town, all voters in that town, pro-Takahashi or pro-Aoki, will vote for Takahashi.
On the other hand, if he does not make a speech in some town, the pro-Aoki voters in that town will vote for Aoki, and the pro-Takahashi voters will not vote.
To get more votes than Aoki, in how many towns does Takahashi need to make speeches at least?

Constraints

• All values in input are integers.
• $1 \le N \le 2 \times 10^5$
• $1 \le A_i, B_i \le 10^9$

Input

Input is given from Standard Input in the following format:

$N$

$A_1$ $B_1$

$\vdots$

$A_N$ $B_N$

Output

Print the answer.

Sample Input 1

4
2 1
2 2
5 1
1 3

Sample Output 1

1

After making a speech in the third town, Aoki and Takahashi will get $5$ and $6$ votes, respectively.

Sample Input 2

5
2 1
2 1
2 1
2 1
2 1

Sample Output 2

3

After making speeches in three towns, Aoki and Takahashi will get $4$ and $9$ votes, respectively.

Sample Input 3

1
273 691

Sample Output 3

1