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 <bits/stdc++.h>
using namespace std;
 
#define rep(i, n) for (int i = 0; i < (n); i++)

int main() {
    int D,G;
    cin >> D >> G;
    int P[D],C[D];
    rep(i,D){
        cin >> P[i] >> C[i];
    }
    int res=INT_MAX;
    for(int bit=0;bit<(1<<D);bit++){
        int point = 0;
        int count =0;
        for(int i=0;i<D;i++){
            if(bit & (1<<i)){
                point += (i+1) * 100 * P[i] + C[i];
                count += P[i];
                //cout <<  i+1 << "*" << 100 << "*" << P[i] << "+" << C[i] << " ";
            }
        }
        //cout << "=" << point << endl;
        if(point < G){
            //cout << "   ";
            for(int j=D-1;0<=j;j--){
                if(!(bit & (1<<j))){
                    int c = ceil((double)(G-point) / ((j+1)*100));
                    //cout << "c=" << c << " ";
                    if(c >= P[j]){ 
                        point += (j+1) * 100 * P[j] + C[j];
                        count += P[j];
                        //cout <<  j+1 << "*" << 100 << "*" << P[j] << "+" << C[j] << " ";
                    }else{
                        point += (j+1) * 100 * c;
                        count += c;
                        //cout <<  j+1 << "*" << 100 << "*" << c << " ";
                    }
                    if(point >= G){
                        break;
                    }
                }
            }
            //cout << "=" << point << endl;
        }
        res = min(res,count);
    }
    cout << res << endl;
    return 0;
}