D - Choose Me /

### 問題文

AtCoder 市で市長選挙が行われます。候補者は青木氏と高橋氏です。

### 制約

• 入力は全て整数
• 1 \le N \le 2 \times 10^5
• 1 \le A_i, B_i \le 10^9

### 入力

N
A_1 B_1
\vdots
A_N B_N


### 入力例 1

4
2 1
2 2
5 1
1 3


### 出力例 1

1


3 番目の町で演説を行うと、青木氏が 5 票、高橋氏が 6 票を得ます。

### 入力例 2

5
2 1
2 1
2 1
2 1
2 1


### 出力例 2

3


3 つの町で演説を行うと、青木氏が 4 票、高橋氏が 9 票を得ます。

### 入力例 3

1
273 691


### 出力例 3

1


Score : 400 points

### 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


### 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