#pragma GCC optimize("Ofast")
#if 1
#define _USE_MATH_DEFINES
#include "bits/stdc++.h"

using namespace std;

using ll = int64_t;
using db = double;
using ld = long double;
using vi = vector<int>;
using vl = vector<ll>;
using vvi = vector<vector<int>>;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vpii = vector<pii>;
using vpll = vector<pll>;

constexpr char newl = '\n';
constexpr double eps = 1e-10;

#define FOR(i,a,b) for (int i = (a); i < (b); i++)
#define F0R(i,b) FOR(i,0,b)
#define RFO(i,a,b) for (int i = ((b)-1); i >=(a); i--)
#define RF0(i,b) RFO(i,0,b)
#define show(x) cerr << #x << " = " << (x) << '\n';
#define rng(a) a.begin(),a.end()
#define rrng(a) a.rbegin(),a.rend()
#define sz(x) (int)(x).size()
#define YesNo(x) cout<<((x)?"Yes":"No")<<newl;
#define YESNO(x) cout<<((x)?"YES":"NO")<<newl;
#define v(T) vector<T>
#define vv(T) vector<vector<T>>

template<class A, class B> using umap = unordered_map<A, B>;
template<class A> using uset = unordered_set<A>;

template<typename T1, typename T2> inline void chmin(T1& a, T2 b) { if (a > b) a = b; }
template<typename T1, typename T2> inline void chmax(T1& a, T2 b) { if (a < b) a = b; }
template<class T> bool lcmp(const pair<T, T>& l, const pair<T, T>& r) {
  return l.first < r.first;
}
template<class T> istream& operator>>(istream& i, v(T)& v) {
  F0R(j, sz(v)) i >> v[j];
  return i;
}
template<class A, class B> istream& operator>>(istream& i, pair<A, B>& p) {
  return i >> p.first >> p.second;
}
template<class A, class B, class C> istream& operator>>(istream& i, tuple<A, B, C>& t) {
  return i >> get<0>(t) >> get<1>(t) >> get<2>(t);
}
template<class T> ostream& operator<<(ostream& o, const pair<T, T>& v) {
  o << "(" << v.first << "," << v.second << ")";
  return o;
}
template<class T> ostream& operator<<(ostream& o, const vector<T>& v) {
  F0R(i, v.size()) {
    o << v[i] << ' ';
  }
  o << newl;
  return o;
}
template<class T> ostream& operator<<(ostream& o, const set<T>& v) {
  for (auto e : v) {
    o << e << ' ';
  }
  o << newl;
  return o;
}
template<class T1, class T2> ostream& operator<<(ostream& o, const map<T1, T2>& m) {
  for (auto& p : m) {
    o << p.first << ": " << p.second << newl;
  }
  o << newl;
  return o;
}



// INSERT ABOVE HERE
signed main() {
  cin.tie(0);
  ios_base::sync_with_stdio(false);

  int N; ll K;
  cin >> N >> K;
  using E = pair<ll, int>;
  v(E) es(N);
  F0R(i, N) {
    ll a; int b; cin >> a >> b;
    es[i] = { a,b };
  }
  sort(rng(es));
  F0R(i, N) {
    auto [a, b] = es[i];
    if (a > K) break;
    K += b;
  }
  cout << K << newl;
}
#endif

//by ciwomuli
//enter ICPC WF 2020
#include <algorithm>
#include <cctype>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
#define LL long long
using namespace std;
template <typename T>
inline void read(T &t)
{
    int f = 0, c = getchar();
    t = 0;
    while (!isdigit(c))
        f |= c == '-', c = getchar();
    while (isdigit(c))
        t = t * 10 + c - 48, c = getchar();
    if (f)
        t = -t;
}
template <typename T, typename... Args>
inline void read(T &t, Args &... args)
{
    read(t);
    read(args...);
}
int main()
{
    int n, x;
    read(n, x);
    x *= 100;
    double sum = 0;
    for (int i = 1; i <= n; i++)
    {
        int a, b;
        read(a, b);
        sum += a * b;
        if (sum > x)
        {
            cout << i;
            return 0;
        }
    }
    cout << -1;
}