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# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
class Program{
	static int[] s;
	static int[][] a;
	static int[] dp;
	static int ans=int.MaxValue;
	static void Main(){
		s=Array.ConvertAll(Console.ReadLine().Split(),int.Parse);
		a=new int[s[0]][];
		dp=new int[1024];
		for(int i=0;i<s[0];i++){a[i]=Array.ConvertAll(Console.ReadLine().Split(),int.Parse);}
		fu(0,0,0);
		Console.WriteLine(ans);
	}
	static void fu(int p,int t,int b){
		if(dp[b]==0){dp[b]=p;}
		else if(dp[b]==p){return;}
		if(t>=ans){return;}
		if(p>=s[1]){ans=t;}
		else{
			for(int i=0;i<s[0];i++){
				if((b&(1<<i))==0){
					fu(p+a[i][1]+a[i][0]*(i+1)*100,t+a[i][0],b|(1<<i));
				}
			}
			
			for(int i=s[0]-1;i>=0;i--){
				if((b&(1<<i))==0){
					if(dp[b|(1<<i)]>=s[1]){
						int q=1;
						while(q!=a[i][0]&&t+q<ans){
							p+=(i+1)*100;
							if(p>=s[1]){ans=t+q;break;}
							q++;
						}
					}
					break;
				}
			}
		}
	}
}