#include<stdio.h>
using namespace std;
int v[1002];
int main()
{
    int n,g,x,y,j,min,i;
    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    scanf("%d%d",&n,&g);
    for(i=1;i<=n;i++)
    {
        scanf("%d%d",&x,&y);
        for(j=1001;j>x;j--)
         {
             if(v[j-x]!=0)
             {
                if(v[j-x]+y<v[j]&&v[j]!=0)
                       v[j]=v[j-x]+y;
                else
                    if(v[j]==0)
                        v[j]=v[j-x]+y;
             }
         }
        if(v[x]==0)
            v[x]=y;
        else
            if(y<v[x])
                v[x]=y;
    }
    min=100000001;
    for(i=1;i<=1001;i++)
        if(v[i]<min&&v[i]>=g)
            min=v[i];
    if(min!=100000001)
        printf("%d",min);
    else
        printf("-1");
    return 0;

}