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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <iostream>
#include <string>
#include <vector>
#include <map>
#include <unordered_map>
#include <queue>
#include <algorithm>

#include <bits/stdc++.h>
#include <cmath>
#include <limits>

using namespace std;

#define MAX 10000

int D;
long long G;
int p[10+2] = {0};
int c[10+2] = {0};
long long C[10+2] = {0};

int main(int argc, char* argv[]){
	cin >> D >> G;

	for(int i = 0; i < D; i++){
		cin >> p[i] >> c[i];
		C[i] = (100 * (i+1) * p[i]) + c[i];
	}

	//コンプリートの有無によるビット全探索
	int ans = 100*10;
	for(int b = 0; b < (1<<D); b++){
		long long point = 0;
		int problems = 0;
		for(int i=0; i<D; i++){
			if( b & (1<<i) ){ //コンプリートする100(i+1)点問題
				point += C[i];
				problems += p[i];
			}
		}
		if(point < G){ //このパターンのコンプリートだけでは不足
			for(int i=D-1; i>=0; i--){ //コンプリートしていない高得点のものから解く
				if( !( b & (1<<i) ) ){ 
					for(int j=1; j<=p[i]-1; j++){ //コンプリートではないので、j=p[i]は除外。
						point += 100 * (i+1);
						problems++;
						if(point >= G){
							break;
						}
					}
				}
				if(point >= G){
					break;
				}
			}
		}
		if(point >= G && ans > problems){
			ans = problems;
		}
	}
	cout << ans << endl;
	return 0;
}