//problema rucsacului

#include <cstdio>


using namespace std;

int i, j, n,v[10005],frec[1000000],sum,aux,e,c,maxi;


int main() {

    freopen("energii.in","r",stdin);
    freopen("energii.out","w",stdout);
    scanf("%d",&n);
    scanf("%d",&sum);

    maxi=100000000;
    for(i = 1; i <= sum; i++)
    {
        frec[i] = 100000000;
    }
    for(i=1;i<=n;i++)
    {

        scanf("%d%d\n",&e,&c);
        for(j=sum;j>=0;j--)
        {
            if(frec[j]!=0 || j == 0)
            {
                if(j+e<=sum)
                {
                    if(frec[j+e]>frec[j]+c )
                    {
                       frec[j+e]=frec[j]+c;
                    }

                }
                else
                {
                    if(maxi>frec[j]+c)
                        maxi=frec[j]+c;

                }

            }
        }
        if(e>sum && maxi>c)
           {
               maxi=c;
           }
    }

    if(maxi!=100000000)
    {
        if(frec[sum] < maxi && frec[sum] != 0)
        {
            printf("%d",frec[sum]);
        }
        else
        {
           printf("%d",maxi);
        }

    }

    else printf("-1\n");
}