#include <bits/stdc++.h>

using namespace std;

ifstream fin("energii.in");
ofstream fout("energii.out");

int Recon[3][10005];
int linie,coloana;
int n,W;
int Eprod,Econs;

int main()
{
 fin>>n;
 fin>>W;
 for (linie=1;linie<=n;linie++)
 {
  fin>>Eprod>>Econs;
  for (coloana=1;coloana<=10000;coloana++)
  {
   Recon[2][coloana]=Recon[1][coloana];
   if (Econs<=coloana)
    Recon[2][coloana]=max(Recon[1][coloana],Recon[1][coloana-Econs]+Eprod);
  }
  for (coloana=1;coloana<=10000;coloana++)
   Recon[1][coloana]=Recon[2][coloana];
 }
 coloana=1;
 while (Recon[1][coloana]<W&&coloana<=10000)
  coloana++;
 if (coloana!=10001)
  fout<<coloana;
 else
  fout<<"-1";
 return 0;
}