#pragma GCC optimize ("O3")
#include <iostream>
#include <iomanip>
#include <istream>
#include <ostream>
#include <sstream>
#include <iterator>
#include <vector>
#include <algorithm>
#include <queue>
#include <deque>
#include <list>
#include <stack>
#include <map>
#include <unordered_map>
#include <set>
#include <bitset>
#include <utility>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <string>
#include <ctime>
#include <cctype>
#include <cstdlib>
#define IINF 10e8
#define INF 1<<30
#define MOD 1000000007
#define mod 10007
#define REP(i, a, n) for (ll i = a; i < (ll)(n); i++)
#define REPE(i, a, n) for (ll i = a; i <= (ll)(n); i++)
#define Endl endl
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define eb emplace_back
#define mmax(x,y)(x>y?x:y)
#define mmin(x,y)(x<y?x:y)
#define chmax(x,y) x=mmax(x,y)
#define chmin(x,y) x=mmin(x,y)
#define all(x) (x).begin(),(x).end()
#define siz(x) (ll)(x).size()
#define PI acos(-1.0)
using namespace std;
typedef long long int ll;
typedef unsigned long long int ull;
typedef long double ld;
typedef pair<int,int>Pin;
typedef pair<ll,ll>Pll;
template<class T> using V=vector<T>;
long long GCD(long long a, long long b) {return b?GCD(b,a%b):a;}
long long LCM(long long a, long long b) {return a/GCD(a,b)*b;}
int dx[4]={-1,0,1,0};
int dy[4]={0,-1,0,1};
int ddx[8]={-1,0,1,0,1,1,-1,-1};
int ddy[8]={0,-1,0,1,1,-1,1,-1};
ll cmp(pair<ll,ll>a,pair<ll,ll> b){
        if(a.se!=b.se)
        return a.se<b.se;
        else
        return a.fi<b.fi;
}
//----------------------------------------------------------------------

//----------------------------------------------------------------------
int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    //-------------------------------  
    //ll begin_time=clock();
    //-------------------------------
    ll D,G;cin>>D>>G;
    V<Pll>pc(D);
    for(ll i=0;i<D;i++){
        ll p,c;cin>>p>>c;
        pc[i].fi=p;pc[i].se=c;
    }
    ll ans=INF;
    for(int bit=0;bit < (1<<D); bit++)//(1<<n)-1是全部都用的状态
    {
        ll cnt=0;
        ll score=0;
        for(int i=0;i<D;i++){
            if(bit & (1<<i)){
                cnt+=pc[i].fi;
                score+=100*pc[i].fi*(i+1)+pc[i].se;
            }
        }
        if(score>=G){
            chmin(ans,cnt);
        }
        else{
            ll c=G-score;
            for(int i=D-1;i>=0;i--){
                if(bit &(1<<i))continue;
                if(c<=0)break;
                ll total=pc[i].fi*(i+1)*100;
                if(total>=c){
                    ll ccnt=c/((i+1)*100);
                    if(c%((i+1)*100)!=0)ccnt++;
                    cnt+=ccnt;
                    c=0;
                }
                else{
                    cnt+=pc[i].fi;
                    c-=total;
                    c-=pc[i].se;
                }

            }
            chmin(ans,cnt);
        }
    }
    cout<<ans<<endl;
    //-------------------------------  
    //ll end_time=clock();cout<<"time="<<end_time-begin_time<<"ms"<<endl;
    //-------------------------------
    return 0;
}
//----------------------------------------------------------------------





























Measured memory_bytes: 256