#include <cstdio>
#include <algorithm>
using namespace std;
int Gmax,n,a[2][10000001],g[1001],v[1001],i,j,k,r;
int main()
{freopen("energii.in","r",stdin);
 freopen("energii.out","w",stdout);
 scanf("%d%d",&n,&k);
 for(i=1;i<=n;i++)
    {scanf("%d%d",&v[i],&g[i]);
     Gmax=Gmax+g[i];
    }
 r=0;
 for(i=1;i<=n;i++)
    {for(j=1;j<=Gmax;j++)
       {if(g[i]>j) a[1][j]=a[0][j];
        else{a[1][j]=max(a[0][j],v[i]+a[0][j-g[i]]);
            }
        if((a[1][j]>=k)&&(j<=Gmax)){Gmax=j;r=1;break;}
       }
     for(j=1;j<=Gmax;j++)
        a[0][j]=a[1][j];
    }
 if(r==1)printf("%d",Gmax);
   else printf("-1");
}