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;


public class C{
	
	public static void Main(){
	
		string[] args;

		args = Console.ReadLine().Split(' ');
		long d = Int64.Parse(args[0]);
		long g = Int64.Parse(args[1]);
		
		long[] p = new long[d+1];
		long[] c = new long[d+1];
		
		for( int i = 1; i <= d; i++ ){
			args = Console.ReadLine().Split(' ');
			p[i] = Int64.Parse(args[0]);
			c[i] = Int64.Parse(args[1]);			
		}
		
		long[] total = new long[d+1];
		for( int i = 1; i <= d; i++ ){
			total[i] = 100 * i * p[i] + c[i];
		}
		
		long minNumSolve = Int64.MaxValue; 
		for( int s = 0; s < (1 << (int)d); s++ ){
			
			long point = 0;
			long numSolve = 0;
			
			for( int i = 0; i < d; i++ ){
				if( ((s >> i) & 1) == 0 ) continue;
				point += total[i+1];
				numSolve += p[i+1];
			}

			if( point >= g ){
				if( numSolve < minNumSolve ) minNumSolve = numSolve;
				continue;			
			}
			
			for( int i = 0; i < d; i++ ){
				long rest = g - point;
				if( ((s >> i) & 1) == 1 ) continue;
				if( rest > 100 * (i + 1) * p[i+1] ) continue;
				long tmpNumSolve = numSolve;
				tmpNumSolve += rest / ( 100 * (i + 1) );
				if( rest % (100 * (i + 1)) != 0 ) tmpNumSolve++;
				if( tmpNumSolve < minNumSolve ) minNumSolve = tmpNumSolve;
			}		
			
		}
		
		Console.WriteLine(minNumSolve);		
		
	}

}