#include<iostream>
using namespace std;
int main()
{
int n,x;
cin>>n>>x;
int s=0,ans=-1;
for(int i=0;i<n;i++)
{
int v,p;
cin>>v>>p;
int t=v*p/100;
s+=t;
if(s>x)
ans=i+1;
}
cout<<ans;
return 0;
}
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