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 Rust (1.15.1) (judge verdict: Accepted)

use std::cmp;
use std::io;

fn main() {
    let mut input = String::new();
    io::stdin().read_line(&mut input).ok();
    let l: Vec<&str> = input.trim().split_whitespace().collect();
    let d: usize = l[0].parse().unwrap();
    let g: usize = l[1].parse().unwrap();
    let mut ans = 999999;

    let mut v: Vec<(usize, usize)> = Vec::new();
    let mut vcomp: Vec<usize> = Vec::new();

    let mut x = 100;
    for _ in 0..d {
        let mut input = String::new();
        io::stdin().read_line(&mut input).ok();
        let l: Vec<&str> = input.trim().split_whitespace().collect();
        v.push((l[0].parse().unwrap(), l[1].parse().unwrap()));
        vcomp.push(v.last().unwrap().0 * x + v.last().unwrap().1);
        x = x + 100;
    }

    for z in 0..2_usize.pow(d as u32) {
        let mut zbuf = z;
        let mut counter = 0;
        let mut sum_complete = 0;
        let mut sum_count = 0;

        while zbuf > 0 {
            if zbuf & 1 != 0 {
                sum_complete += vcomp[counter];
                sum_count += v[counter].0;
            }
            counter += 1;
            zbuf >>= 1;
        }

        let mut s = d;

        while sum_complete < g {
            s -= 1;
            if (2_usize.pow(s as u32) & z) != 0 {
                if s == 0 {
                    break;
                }
                continue;
            }

            let pp = (s + 1) * 100;
            let mut rest = v[s].0 - 1;

            while rest > 0 {
                sum_count += 1;
                sum_complete += pp;
                if sum_complete >= g {
                    break;
                }
                rest -= 1;
            }

            if s == 0 {
                break;
            }
        }

        if sum_complete < g {
            sum_count = 99999999;
        }
        ans = cmp::min(ans, sum_count);
    }

    println!("{}", ans);
}