
#include <iostream>
using namespace std;

int main()
{
  int N, X;
  cin >> N >> X;
  X *= 100;
  int x = 0;
  for (int n = 1; n <= N; ++n)
  {
    int V, P;
    cin >> V >> P;
    x += V*P;
    if (X < x)
    {
      cout << n << endl;
      return 0;
    }
  }
  cout << -1 << endl;
  return 0;
}

#include <bits/stdc++.h>
using namespace std;
#define fast_io cin.tie(0);ios_base::sync_with_stdio(0);
string to_string(string s) { return '"' + s + '"';}
string to_string(char s) { return string(1, s);}
string to_string(const char* s) { return to_string((string) s);}
string to_string(bool b) { return (b ? "true" : "false");}
template <typename A> string to_string(A);
template <typename A, typename B>string to_string(pair<A, B> p) {return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";}
template <typename A> string to_string(A v) {bool f = 1; string r = "{"; for (const auto &x : v) {if (!f)r += ", "; f = 0; r += to_string(x);} return r + "}";}
void debug_out() { cout << endl; }
void show() { cout << endl; }
void pret() { cout << endl; exit(0);}
template <typename Head, typename... Tail> void debug_out(Head H, Tail... T) {cout << " " << to_string(H); debug_out(T...);}
template <typename Head, typename... Tail> void show(Head H, Tail... T) {cout <<H<<" "; show(T...);}
template <typename Head, typename... Tail> void pret(Head H, Tail... T) {cout <<H<<" "; pret(T...);}
#define pr(...) cout << "[" << #__VA_ARGS__ << "]:", debug_out(__VA_ARGS__)
typedef long long ll;
#define int ll
typedef long double ld;
typedef vector<int> vi;
#define disp(x) cout<<x<<" ";
#define rep(i,a,b) for(int i=a;i<(int)b;i++)
#define fo(i,a,b) for(int i=a;i<=(int)b;i++)
#define rf(i,a,b) for(int i=a;i>=(int)b;i--)
#define mp make_pair
#define pb emplace_back
#define F first
#define S second
#define endl '\n'
//cout.setf(ios::fixed);cout.precision(18)
const int MOD = 1e9+7;
const int maxn = 300000+10;

int32_t main(){
    fast_io;
    int n, x;
    cin >> n >> x;
    x *= 100;
    int val = 0;
    fo(i, 1, n){
    	int v, p;
    	cin >> v >> p;
    	val += (v * p);
    	if(val > x){
    		pret(i);
    	}
    }
    show(-1);
    return 0;
}