#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <tuple>
#include <deque>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
using namespace std;

typedef long long ll;
typedef pair<int, int> P;
typedef pair<int, double> Pid;
typedef pair<double, int> Pdi;
typedef pair<ll, int> Pl;
const double PI = 3.1415926535897932;   // acos(-1)
const double EPS = 1e-15;
const int INF = 1001001001;
const ll mod = 1e+9 + 7;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define chadd(x, y) x = (x + y) % mod

template<typename Monoid>
struct SegmentTree{
    using F = function<Monoid(Monoid, Monoid)>;

    int sz;
    vector<Monoid> seg;

    const F f;      // モノイドに対して二項演算を行う関数オブジェクト
    const Monoid M1;

    SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1){
        sz = 1;
        while(sz < n)   sz <<= 1;
        seg.assign(2 * sz, M1);
    }

    void set(int k, const Monoid &x){
        seg[k + sz] = x;
    }

    void build(){
        for(int k = sz - 1; k > 0; --k){
            seg[k] = f(seg[k << 1], seg[k << 1 | 1]);
        }
    }

    void update(int k, const Monoid &x){
        k += sz;
        seg[k] = x;
        while(k >>= 1){
            seg[k] = f(seg[k << 1], seg[k << 1 | 1]);
        }
    }

    Monoid query(int a, int b){
        Monoid L = M1, R = M1;
        for(a += sz, b += sz; a < b; a >>= 1, b >>= 1){
            if(a & 1)   L = f(L, seg[a++]);
            if(b & 1)   R = f(seg[--b], R);
        }
        return f(L, R);
    }

    Monoid operator[](const int &k) const{
        return seg[k + sz];
    }
};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int d, g;
    cin >> d >> g;
    vector<vector<int>> score(d);
    for(int i = 0; i < d; ++i){
        int p, c;
        cin >> p >> c;
        for(int j = 0; j < p; ++j){
            int hoge = 100 * (i + 1) * (j + 1);
            if(j == p - 1){
                score[i].push_back(hoge + c);
            }
            else{
                score[i].push_back(hoge);
            }
        }
    }

    int res = INF;
    for(int mask = 0; mask < (1 << d); ++mask){
        vector<int> zero, one;
        for(int i = 0; i < d; ++i){
            if(mask & (1 << i)) one.push_back(i);
            else    zero.push_back(i);
        }
        int sz0 = zero.size(), sz1 = one.size();
        int now_score = g;
        int cnt = 0;
        for(int i = 0; i < sz1; ++i){
            int sz = score[one[i]].size();
            now_score -= score[one[i]][sz - 1];
            cnt += sz;
        }
        if(now_score <= 0){
            chmin(res, cnt);
            continue;
        }
        for(int i = sz0 - 1; i >= 0; --i){
            int sz = score[zero[i]].size() - 1;
            if(sz == 0) continue;
            int pos = lower_bound(score[zero[i]].begin(), score[zero[i]].begin() + sz, now_score) - score[zero[i]].begin();
            if(pos != sz){
                now_score -= score[zero[i]][pos];
                cnt += pos + 1;
                break;
            }
            else{
                now_score -= score[zero[i]][pos - 1];
                cnt += pos;
            }
        }
        if(now_score <= 0)  chmin(res, cnt);
    }

    cout << res << "\n";
}

Measured memory_bytes: 256