CF1209B.Koala and Lights

普及/提高-

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题目描述

It is a holiday season, and Koala is decorating his house with cool lights! He owns $n$ lights, all of which flash periodically.

After taking a quick glance at them, Koala realizes that each of his lights can be described with two parameters $a_i$ and $b_i$ . Light with parameters $a_i$ and $b_i$ will toggle (on to off, or off to on) every $a_i$ seconds starting from the $b_i$ -th second. In other words, it will toggle at the moments $b_i$ , $b_i + a_i$ , $b_i + 2 \cdot a_i$ and so on.

You know for each light whether it's initially on or off and its corresponding parameters $a_i$ and $b_i$ . Koala is wondering what is the maximum number of lights that will ever be on at the same time. So you need to find that out.

Here is a graphic for the first example.

输入格式

The first line contains a single integer $n$ ( $1 \le n \le 100$ ), the number of lights.

The next line contains a string $s$ of $n$ characters. The $i$ -th character is "1", if the $i$ -th lamp is initially on. Otherwise, $i$ -th character is "0".

The $i$ -th of the following $n$ lines contains two integers $a_i$ and $b_i$ ( $1 \le a_i, b_i \le 5$ ) — the parameters of the $i$ -th light.

输出格式

Print a single integer — the maximum number of lights that will ever be on at the same time.

输入输出样例

输入#1
```
3
101
3 3
3 2
3 1
```
输出#1
```
2
```
输入#2
```
4
1111
3 4
5 2
3 1
3 2
```
输出#2
```
4
```
输入#3
```
6
011100
5 3
5 5
2 4
3 5
4 2
1 5
```
输出#3
```
6
```

说明/提示

For first example, the lamps' states are shown in the picture above. The largest number of simultaneously on lamps is $2$ (e.g. at the moment $2$ ).

In the second example, all lights are initially on. So the answer is $4$ .

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