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::io::*;
fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let g: usize = itr.next().unwrap().parse().unwrap();
    let pc: Vec<(usize, usize)> = (0..n)
        .map(|_| {
            (
                itr.next().unwrap().parse().unwrap(),
                itr.next().unwrap().parse().unwrap(),
            )
        })
        .collect();

    // g以上
    let mut ans = 1usize << 60;
    for bit in 0..1 << n {
        let mut tc = 0;
        let mut tp = 0;
        for i in 0..n {
            if bit >> i & 1 == 1 {
                tc += pc[i].0;
                tp += pc[i].1 + pc[i].0 * 100 * (i + 1);
            }
        }
        // 足りない分解く
        if tp >= g {
            ans = std::cmp::min(ans, tc);
        } else {
            // 大きいほうコアラ
            let mut ok = false;
            for i in (0..n).rev() {
                if bit >> i & 1 == 0 {
                    for _ in 0..pc[i].0 {
                        tc += 1;
                        tp += 100 * (i + 1);
                        if tp >= g {
                            ok = true;
                            break;
                        }
                    }
                }
                if ok {
                    break;
                }
            }
            if ok {
                ans = std::cmp::min(ans, tc);
            }
        }
    }
    println!("{}", ans);
}