#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.in");
int n,w,mi,i,s,j,v[10001],gr[10001],b[10001];
int main()
{f>>n>>w;
s=0;
for(i=1;i<=n;++i)
    {f>>gr[i]>>v[i];
    s=s+v[i];
    }
b[0]=1;
for(i=1;i<=n;++i)
    {for(j=s;j>=1;--j)
    if(b[j]!=0&&b[j+gr[i]]<b[j]+v[i])
    b[i+gr[i]]=b[j]+v[i];
    if(v[i]>b[gr[i]])
        b[gr[i]]=v[i];
    }
mi=9999999;
for(i=w;i<=s;++i)
    if(b[i]>=w&&b[i]<mi)
    mi=b[i];
if(mi==99999999)
    g<<"-1"<<'\n';
else
    g<<mi<<'\n';
return 0;
}