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 Go (1.14.1) (judge verdict: Accepted)

package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner((os.Stdin))

func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func nextInt() int {
	l := nextLine()
	i, e := strconv.Atoi(l)
	if e != nil {
		panic(e)
	}
	return i
}

func main() {
	sc.Split(bufio.ScanWords)
	D, G, p, c := nextInt(), nextInt(), []int{}, []int{}
	for i := 0; i < D; i++ {
		p = append(p, nextInt())
		c = append(c, nextInt())
	}

	fmt.Printf("%d\n", ABC104C(G, p, c))
}

// ABC104C ...
func ABC104C(G int, p, c []int) (res int) {
	res = 1000
	for bit := 0; bit < (1 << uint(len(c))); bit++ {
		ans, score, solved := 0, 0, map[int]bool{}
		for i := 0; i < len(c); i++ {
			if bit>>uint(i)&1 == 1 {
				ans += p[i]
				score += c[i] + (i+1)*100*p[i]
				solved[i] = true
			}
		}

		if score < G {
			for i := len(p) - 1; i >= 0; i-- {
				_, ok := solved[i]
				if !ok {
					rest := G - score
					if rest > (i+1)*100*(p[i]-1) {
						ans += p[i] - 1
						score += (i + 1) * 100 * (p[i] - 1)
					} else {
						solvedhrere := rest / ((i + 1) * 100)
						ans += solvedhrere
						score += (i + 1) * 100 * solvedhrere
					}
				}
			}
		}

		if score >= G && ans < res {
			res = ans
		}
	}
  
  	return
}