#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
using u64 = unsigned long long;
#define REP(i, n) for (int i = 0; i < (i64)(n); ++i)
#define WHOLE(x) std::begin(x), std::end(x)
#define LEN(a) int((a).size())

template <class T>
bool chmax(T &a, T b) {
  if (a < b) return (a = move(b)), true;
  return false;
}
template <class T>
bool chmin(T &a, T b) {
  if (a > b) return (a = move(b)), true;
  return false;
}

template <typename T>
using V = std::vector<T>;
template <typename T>
vector<T> make_vec(size_t n, T a) {
  return vector<T>(n, a);
}
template <typename... Ts>
auto make_vec(size_t n, Ts... ts) {
  return vector<decltype(make_vec(ts...))>(n, make_vec(ts...));
}
template <typename T>
istream &operator>>(istream &is, vector<T> &a) {
  for (auto &x : a) is >> x;
  return is;
}
template <typename Container>
ostream &pprint(const Container &a, string_view sep = " ",
                string_view ends = "\n", ostream *os = nullptr) {
  if (os == nullptr) os = &cout;
  auto b = std::begin(a), e = std::end(a);
  for (auto it = std::begin(a); it != e; ++it) {
    if (it != b) *os << sep;
    *os << *it;
  }
  return *os << ends;
}
template <typename T>
ostream &operator<<(ostream &os, const vector<T> &a) {
  return pprint(a, ", ", "", &(os << "[")) << "]";
}
template <typename T>
ostream &operator<<(ostream &os, const set<T> &a) {
  return pprint(a, ", ", "", &(os << "{")) << "}";
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const map<T, U> &a) {
  return pprint(a, ", ", "", &(os << "{")) << "}";
}
template <typename T, typename U>
ostream &operator<<(ostream &os, const pair<T, U> &a) {
  return os << "(" << a.first << ", " << a.second << ")";
}

#ifdef ENABLE_DEBUG
template <typename T>
void debug(T value) {
  cerr << value;
}
template <typename T, typename... Ts>
void debug(T value, Ts... args) {
  cerr << value << ", ";
  debug(args...);
}
#define DEBUG(...)                              \
  do {                                          \
    cerr << " \033[33m (L" << __LINE__ << ") "; \
    cerr << #__VA_ARGS__ << ":\033[0m ";        \
    debug(__VA_ARGS__);                         \
    cerr << endl;                               \
  } while (0)
#else
#define debug(...)
#define DEBUG(...)
#endif

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int D, G;
  cin >> D >> G;
  V<int> P(D), C(D);
  REP(i, D) { cin >> P[i] >> C[i]; }

  int ans = accumulate(WHOLE(P), 0);
  int L = 1 << D;
  REP(bits, L) {
    i64 score = 0;
    int num_solved = 0;
    REP(i, D) {
      if (bits & (1 << i)) {
        score += C[i];
        score += (i + 1) * 100 * P[i];
        num_solved += P[i];
      }
    }
    if (num_solved >= ans) continue;
    if (score < G) {
      for (int i = D - 1; i >= 0; --i) {
        if (bits & (1 << i)) continue;
        int pt = (i + 1) * 100;  // points per problem
        int gain = pt * P[i];
        if (score + gain < G) {
          score += gain;
          num_solved += P[i];
          continue;
        }
        int k = (G - score + pt - 1) / pt;
        assert(k <= P[i]);  // should solve k problems.
        assert(score + pt * k >= G);
        score += pt * k;
        num_solved += k;
        break;
      }
    }
    if (score >= G) {
      chmin(ans, num_solved);
    }
  }
  cout << ans << endl;
}


Measured memory_bytes: 3636