#include<fstream>
using namespace std;
ifstream fin("energii.in");
ofstream fout("energii.out");
int n,w,s,E[1001],C[1001],V[1001*10001];
int main()
{
    int i,j;
    fin>>n>>w;
    for (i=1;i<=n;++i)
        fin>>E[i]>>C[i], s+=C[i];
    for (i=1;i<=n;++i)
        for (j=s;j>=C[i];--j)
            V[j]=max(V[j],V[j-C[i]]+E[i]);
    for (i=1;i<=s;++i)
        if (V[i]>=w)
            {
                fout<<i<<'\n';
                break;
            }
    if (i==n+1) fout<<"-1\n";
    return 0;
}