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::*;
use std::str::FromStr;

#[allow(dead_code)]
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

fn calc(depth: usize, g: i64, used: usize, cnts: &Vec<i64>, cs: &Vec<i64>) -> usize {
    let n = cnts.len();
    if depth == n {
        let mut ans = 0;
        let mut sum = 0;
        for i in 0..n {
            if ((used >> i) & 1) == 1 {
                let p = (i + 1) as i64 * 100;
                sum += p * cnts[i] + cs[i];
                ans += cnts[i];
            }
        }
        for i in (0..n).rev() {
            if ((used >> i) & 1) == 1 {
                continue;
            }
            let p = (i + 1) as i64 * 100;
            let c = std::cmp::max(0, std::cmp::min((g - sum + p - 1) / p, cnts[i]));
            sum += p * c;
            ans += c;
        }
        return ans as usize;
    }
    let ans = std::cmp::min(
        calc(depth + 1, g, used, cnts, cs),
        calc(depth + 1, g, used | (1 << depth), cnts, cs),
    );
    return ans;
}

fn main() {
    let n = read::<usize>();
    let g = read::<i64>();
    let mut cnts = vec![0; n];
    let mut cs = vec![0; n];
    for i in 0..n {
        cnts[i] = read::<i64>();
        cs[i] = read::<i64>();
    }
    let ans = calc(0, g, 0, &cnts, &cs);
    println!("{}", ans);
}