//problema rucsacului

#include <cstdio>


using namespace std;

int i, j, n,v[1005],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<=n;i++)
    {

        scanf("%d%d\n",&e,&c);
        for(j=sum-1;j>=1;j--)
        {
            if(frec[j]!=0)
            {
                if(j+e<sum)
                {
                if(frec[j+e]>frec[j]+c)
                {
                   frec[j+e]=frec[j]+c;
                }

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

                }

            }
        }
        if(frec[c]>e || frec[c]==0)
            frec[c]=e;
    }

    for(i=1;i<=sum;i++)
    {
        //printf("%d ",frec[i]);
    }
    if(maxi!=100000000)
    printf("%d",maxi);
    else printf("-1");
}