#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;
		
}
	
	




		


    
	


		
#include <iostream>
#include <vector>

using namespace std;
using ll = long long;

int main() {
    int N;
    ll X;
    cin >> N >> X;

    vector<ll> V(N);
    vector<ll> P(N);

    for (int i = 0; i < N; ++i) {
        cin >> V.at(i) >> P.at(i);
    }

    ll total = 0;

    for (int i = 0; i < N; ++i) {
        total += P.at(i) * V.at(i);

        if(total > X * 100){
            cout << i + 1 << endl;
            return 0;
        }
    }

    cout << -1 << endl;
    return 0;
}