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