Problem:
Score : 300 points

Problem Statement

A programming competition site AtCode provides algorithmic problems.
Each problem is allocated a score based on its difficulty.
Currently, for each integer i between 1 and D (inclusive), there are p_i problems with a score of 100i points.
These p_1 + … + p_D problems are all of the problems available on AtCode.

A user of AtCode has a value called total score.
The total score of a user is the sum of the following two elements:

Base score: the sum of the scores of all problems solved by the user.

Perfect bonuses: when a user solves all problems with a score of 100i points, he/she earns the perfect bonus of c_i points, aside from the base score (1 ≤ i ≤ D).

Takahashi, who is the new user of AtCode, has not solved any problem.
His objective is to have a total score of G or more points.
At least how many problems does he need to solve for this objective?

Constraints

1 ≤ D ≤ 10

1 ≤ p_i ≤ 100

100 ≤ c_i ≤ 10^6

100 ≤ G

All values in input are integers.

c_i and G are all multiples of 100.

It is possible to have a total score of G or more points.

Input

Input is given from Standard Input in the following format:

D G
p_1 c_1
:
p_D c_D

Output

Print the minimum number of problems that needs to be solved in order to have a total score of G or more points. Note that this objective is always achievable (see Constraints).

Sample Input 1

2 700
3 500
5 800

Sample Output 1

3

In this case, there are three problems each with 100 points and five problems each with 200 points. The perfect bonus for solving all the 100-point problems is 500 points, and the perfect bonus for solving all the 200-point problems is 800 points. Takahashi's objective is to have a total score of 700 points or more.

One way to achieve this objective is to solve four 200-point problems and earn a base score of 800 points. However, if we solve three 100-point problems, we can earn the perfect bonus of 500 points in addition to the base score of 300 points, for a total score of 800 points, and we can achieve the objective with fewer problems.

Sample Input 2

2 2000
3 500
5 800

Sample Output 2

7

This case is similar to Sample Input 1, but the Takahashi's objective this time is 2000 points or more. In this case, we inevitably need to solve all five 200-point problems, and by solving two 100-point problems additionally we have the total score of 2000 points.

Sample Input 3

2 400
3 500
5 800

Sample Output 3

2

This case is again similar to Sample Input 1, but the Takahashi's objective this time is 400 points or more. In this case, we only need to solve two 200-point problems to achieve the objective.

Sample Input 4

5 25000
20 1000
40 1000
50 1000
30 1000
1 1000

Sample Output 4

66

There is only one 500-point problem, but the perfect bonus can be earned even in such a case.

Solution in PHP7 (7.0.15) (judge verdict: Accepted)

<?php

$args = [];
$input = explode(' ', trim(fgets(STDIN)));

$d = (int)$input[0];
$g = (int)$input[1];

$cnt = 0;
$probrems = [];
$flg = 0;
$total_amount = 0;
for ($i=1; $i <= $d ; $i++) { 
	$input = explode(' ', trim(fgets(STDIN)));
	$probrems[$i] = [
		'point'  => $i * 100,
		'amount' => (int)$input[0],
		'bonus'  => (int)$input[1],
		'total'  => (int)$input[0] * $i * 100 + (int)$input[1],
		'point_only'  => ((int)$input[0]-1) * $i * 100,
	];
	$flg += pow(2, $i-1);
	$total_amount += (int)$input[0];
}

$min = $total_amount + 1;
for ($i=0; $i <= $flg; $i++) { 
	$bin = decbin($i);
	$len = strlen($bin);
	$tmp_sum = 0;
	$tmp_cnt = 0;
	$used = [];
	for ($k=$len; $k>0; $k--) { 
		$tmp_flg = $bin[$k-1];
		if ($tmp_flg == '1') {
			$tmp_sum += $probrems[$len - $k + 1]['total'];
			$tmp_cnt += $probrems[$len - $k + 1]['amount'];
			$used[] = $len - $k + 1;
		}
	}
	
	if ($tmp_sum >= $g) {
		$min = min($min, $tmp_cnt);
	}else{
		for ($j=$d; $j > 0; $j--) { 
			if (!in_array($j, $used) && $probrems[$j]['point_only'] + $tmp_sum >= $g) {
				$tmp_cnt += (int)ceil(($g - $tmp_sum) / $probrems[$j]['point']);
				$min = min($min, $tmp_cnt);
				break;
			}
		}
	}
}
echo $min;