#include <fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
int n,s,sp,putere,cost,i,m[1005][2],mini=99999999,x,y,z;
int main()
{
    f>>n;
    f>>s;
    for(i=1;i<=n;i++)
    {
        f>>putere;
        sp+=putere;
        f>>cost;
        m[i][0]=putere;m[i][1]=cost;
    }
    if(sp<s)
        g<<"-1";
    else
    {
      for(x=1;x<=n;x++)
        {
            for(y=1;y<=n-x+1;y++)
            {cost=0;putere=0;
                for(z=y;z<=y+x-1;z++)
                {
                    putere+=m[z][0];
                    cost+=m[z][1];
                }
                if(putere>=s)
                    if(cost<mini)
                        {mini=cost;}
            }
        }
        g<<mini;
    }
}