#include <bits/stdc++.h>
using namespace std;
 
int main() {
  
  int N;
  int64_t X;
  cin >> N >> X;
  
  X *= 100;
  
  
 
  int64_t ans = 0;
 
  for (int i = 0; i < N; i++) {
    int64_t V,P;
    cin >> V >> P;
    ans += V*P;
    if(ans > X){
      cout << i+1 << endl;
      return 0;
    }
 
  }
 
  cout << -1 << endl;
}
#include<bits/stdc++.h>
#include <iterator>
#include <iostream>
#include <numeric>
#include <math.h>
#define ll long long
#define ull long
#define mpa make_pair
#define pb push_back
#define ff first
#define pii pair<ll,ll>
#define dd double
#define trace(x) cerr << #x << " : " << x << endl
#define ss second
#define boost ios_base::sync_with_stdio(0)
#define forp(i,a,b) for(ll i=a;i<=b;i++)
#define rep(i,n)    for(ll i=0;i<n;++i)
#define ren(i,n)    for(ll i=n-1;i>=0;i--)
#define forn(i,a,b) for(ll i=a;i>=b;i--)
#define all(c) (c).begin(),(c).end()
#define tr(c,i) for(typeof((c).begin()) i = (c).begin(); i != (c).end();
#define sc(x) scanf("%lld",&x)
#define clr(x,val) memset(x,val,sizeof(x))
#define pr(x) printf("%lld\n",x) 
#define pdd pair<dd,dd>
#define read_arr(a,n) for(ll i=1;i<=n;i++)cin>>a[i];
#define init_arr(a,n) for(ll i=1;i<=n;i++)a[i]=n-i+1;
#define prec(x) cout<<fixed<<setprecision(x)
#define fre freopen("input.txt","r",stdin),freopen("output.txt","w",stdout)
#define arr array 
using namespace std;
ll a[200005];
int main(){
	ll n,x;
	cin>>n>>x;
	ll tot=0;
	ll sol=-1;
	for(ll i=1;i<=n;i++){
		ll v,p;
		cin>>v>>p;
		tot+=v*p;
		if(tot>x*100 and sol==-1){
			sol=i;
		}
	}
	cout<<sol;
		
}
	
	




		


    
	


		