#include<bits/stdc++.h>
using namespace std;
int main()
{
	int ans=-1;
	int total=0,sum=0;
	int n;
	cin>>n>>sum;
	sum=sum*100;
	for(int i=1;i<=n;i++)
	{
		int v,p;
		cin>>v>>p;
		int now=v*p;
		total+=now;
		//cout<<total; 
	//	cout<<total<<now<<endl;
		if(total>sum)
		{
			ans=i;
			break;	
		}
	}
	cout<<ans;
	return 0;
}