#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

int main()
{
    ll n, x;
    cin >> n >> x;
    vector<ll> v(n);
    vector<ll> p(n);
    rep(i, n) cin >> v.at(i) >> p.at(i);

    ll ans = -1;
    x *= 100;
    ll sum = 0;
    rep(i, n)
    {
        sum += v.at(i) * p.at(i);
        if (sum > x)
        {
            ans = i + 1;
            break;
        }
    }

    cout << ans << endl;
    return 0;
}
//#pragma GCC optimize(2)
#include<cstdio>
#include<iostream>
#include<string>
#include<cstring>
#include<map>
#include<cmath>
#include<cctype>
#include<vector>
#include<set>
#include<queue>
#include<algorithm>
#include<sstream>
#include<ctime>
#include<cstdlib>
#define X first
#define Y second
#define L (u<<1)
#define R (u<<1|1)
#define pb push_back
#define mk make_pair
#define Mid (tr[u].l+tr[u].r>>1)
#define Len(u) (tr[u].r-tr[u].l+1)
#define random(a,b) ((a)+rand()%((b)-(a)+1))
#define db puts("---")
using namespace std;

//void rd_cre() { freopen("d://dp//data.txt","w",stdout); srand(time(NULL)); }
//void rd_ac() { freopen("d://dp//data.txt","r",stdin); freopen("d://dp//AC.txt","w",stdout); }
//void rd_wa() { freopen("d://dp//data.txt","r",stdin); freopen("d://dp//WA.txt","w",stdout); }

typedef long long LL;
typedef unsigned long long ULL;
typedef pair<int,int> PII;

const int N=1000010,mod=1e9+7,INF=0x3f3f3f3f;
const double eps=1e-8;

int n;
double x,sum;

int main()
{
//	ios::sync_with_stdio(false);
//	cin.tie(0);

	cin>>n>>x;
	bool f=false;
	int ans=0;
	for(int i=1;i<=n;i++)
	{
		int v,p; scanf("%d%d",&v,&p);
		sum+=v*1.0*p/100;
		if(sum-x>eps&&!f) f=1,ans=i;
	}
	if(f) printf("%d\n",ans);
	else printf("-1\n");




















	return 0;
}
/*

*/








