#include <bits/stdc++.h>
using namespace std;

#ifdef LOCAL
#define debug(var) cerr << (#var) << " = " << (var) << endl;
#else
#define debug(var)
#endif

void init() {
  ios_base::sync_with_stdio(0);
  cin.tie(0); cout.tie(0);
}

const int N = 12;
const int S = 1e5+5501;

int dp[N][S];
int p[N], c[N];

int rek(int pos, int tot) {
  if (tot <= 0) return 0;
  if (pos < 0) return 1e4;
  int &ret = dp[pos][tot];
  if (ret != -1) return ret;
  ret = rek(pos-1, tot);
  for (int i = 1; i < p[pos]; ++i) {
    ret = min(ret, i+rek(pos-1, tot-i*(pos+1)));
  }
  return ret = min(ret, p[pos]+rek(pos-1, tot-p[pos]*(pos+1)-c[pos]));
}

void solve() {
  memset(dp, -1, sizeof(dp));
  int d, g; scanf("%d%d", &d, &g);
  g /= 100;
  for (int i = 0; i < d; ++i) {
    scanf("%d%d", p+i, c+i);
    c[i] /= 100;
  }
  printf("%d", rek(d-1, g));
}

int main() {
  init();
  int t = 1; //scanf("%d", &t);
  while (t--) {
    solve();
  }
  return 0;
}

#include <bits/stdc++.h>
#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace std;
using ll = long long;
using vi=vector<int>;
using P = pair<int,int>;
using Graph = vector<vector<int>>;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);
    
    int d;
    ll g;
    cin >> d >> g;
    vector<int> p(d);
    vector<ll> c(d),a(d);
    rep(i,d){
        cin >> p[i] >> c[i];
    }
    rep(i,d){
        a[i]=(i+1)*100*(p[i]-1);
    }
    ll ans=100000000000000000;
    for(int bit=0;bit<(1<<d);++bit){
        ll pr=0,preans=0;
        vector<int> t;
        for(int i=0;i<d;++i){
            if(bit&(1<<i)){
                pr+=((i+1)*100*p[i]+c[i]);
                preans+=p[i];
            }else{
                t.push_back(i);
            }
        }
        int x=0;
        ll res=0;
        for(auto u:t){
            if(res<a[u]) x=u;
            res=max(res,a[u]);
        }
        if(g>pr){
            ll y=g-pr;
            if(y%(100*(x+1))!=0 && (pr+res)>=g){
                preans+=(y/(100*(x+1))+1);
            }else if(y%(100*(x+1))==0 && (pr+res)>=g){
                preans+=y/(100*(x+1));            
            }else{
                continue;
            }
        }
        ans=min(ans,preans);
    }
    cout << ans << "\n";
    return 0;
}   