#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <algorithm>
#include <cassert>
#include <cfloat>
#include <complex>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <vector>

using namespace std;

#define chmax(x, y) x = max(x, y)
#define chmin(x, y) x = min(x, y)
#define rep(i, n) for (ll i = 0; i < (n); ++i)
#define repLRE(i, l, r) for (ll i = (l); i <= (r); ++i)
#define rrepLRE(i, l, r) for (ll i = (l); i >= (r); --i)
#define Sort(v) sort(v.begin(), v.end())
#define rSort(v) sort(v.rbegin(), v.rend())
#define Reverse(v) reverse(v.begin(), v.end())
#define Lower_bound(v, x) \
  distance(v.begin(), lower_bound(v.begin(), v.end(), x))
#define Upper_bound(v, x) \
  distance(v.begin(), upper_bound(v.begin(), v.end(), x))

using ll = long long;
using ull = unsigned long long;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vll = vector<ll>;
using vP = vector<P>;
using vT = vector<T>;
using vvll = vector<vector<ll>>;
using vvP = vector<vector<P>>;
using dqll = deque<ll>;

ll dx[9] = {-1, 1, 0, 0, -1, -1, 1, 1, 0};
ll dy[9] = {0, 0, -1, 1, -1, 1, -1, 1, 0};

/* Macros reg. ends here */

const ll INF = 1LL << 50;

int main() {
  // ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cout << fixed << setprecision(15);

  ll n, g;
  cin >> n >> g;
  g /= 100;

  vll ps(n), cs(n);
  rep(i,n) {
    cin >> ps[i] >> cs[i];
    cs[i] /= 100;
  }

  ll ans = INF;
  rep(s, 1 << n){
    ll tmp = 0;
    ll scr = 0;
    rep(j, n){
      if((s >> j) & 1) {
        tmp += ps[j];
        scr += (j+1)*ps[j]+cs[j];
      }
    }
    ll cur = n - 1;
    ll curn = 0;
    bool ok = true;
    while(g > scr){
      if(cur < 0){
        ok = false;
        break;
      }
      if((s >> cur) & 1){
        cur--;
        curn = 0;
        continue;
      }
      if(curn == ps[cur]-1){
        cur--;
        tmp += curn-1;
        curn = 0;
      }
      scr += cur + 1;
      curn++;
    }
    tmp += curn;
    if(ok) chmin(ans, tmp);
  }

  cout << ans << endl;

  return 0;
}

#include<cstdio>
#include<math.h>
#include<algorithm>
#include<vector>
#include<queue>
#include<string>
#include<set>
#include<cstring>
#include<map>
 
 
using namespace std;
#define int long long int
#define rep(i,n) for(int i=0;i<n;i++)
#define INF 1001001001
#define LLINF 1001001001001001001
#define mp make_pair
#define pb push_back
#define mod 1000000007
//#define mod 998244353

int D,G;
int p[15],c[15];
int dp[15][1500];
signed main(){
    scanf("%lld %lld",&D,&G);
    int maxp=0;
    rep(i,D){
        scanf("%lld %lld",&p[i],&c[i]);
        maxp=max(maxp,p[i]);
    }
    rep(i,D+1)rep(j,D*maxp+1)dp[i][j]=-INF;
    rep(i,D){
        rep(j,D*maxp+1){
            if(i==0&&j==0)dp[i][j]=0;
            rep(p_num,p[i]+1){
                if(p_num!=p[i])dp[i+1][j+p_num]=max(dp[i+1][j+p_num],dp[i][j]+p_num*(i+1)*100);
                else dp[i+1][j+p_num]=max(dp[i+1][j+p_num],dp[i][j]+p_num*(i+1)*100+c[i]);
            }
        }
    }
    int ans=-1;
    rep(j,D*maxp+1){
        //printf("%lld/",dp[D][j]);
        if(dp[D][j]>=G){ans=j;break;}
    }
    printf("%lld\n",ans);
}