#include<iostream>
#include<fstream>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");

int n, cant,e[1001], c[1001], a[10000000];

int main()
{
    int i,j, m,rez;
    f>>n>>cant;
    for(i=1;i<=n;i++)
        f>>e[i]>>c[i];
    a[0]=m=0;
    for(i=1;i<=n;i++)
        for(j=m;j>=0;j--)
        {
            a[j+e[i]]=a[j]+c[i];
            if(j+e[i]>m)
                m=j+e[i];
        }
       
    rez=10000000;
    for(i=1;i<=cant;i++)
        if(rez>a[i]&&a[i])
            rez=a[i];
    if(rez==0)
        g<<-1<<'\n';
	else
		g<<rez;
    return 0;
}