#include<stdio.h>
#include<algorithm>

int vec[1000001];

struct gen{int en;int cost;};
gen v[10001];

bool sortare (gen a,gen b)
    {return a.en>b.en;}

using namespace std;

int main()

{

freopen ("energii.in","r",stdin);
freopen ("energii.out","w",stdout);

int de_licious=1,i,j,nrcentrale,costlimita;

scanf ("%d%d",&nrcentrale,&costlimita);

for (i=1;i<=nrcentrale;i++)
    scanf ("%d%d",&v[i].en,&v[i].cost);

sort (v+1,v+nrcentrale+1,sortare);

for (i=1;i<=nrcentrale;i++){
    for (j=1000000;j>=1;j--){
        if (vec[j]!=0)
            vec[j+v[i].en]=v[i].cost;}
    vec[v[i].en]+=v[i].cost;}

printf ("-1");


return 0;
}