#include <fstream>

using namespace std;

ifstream f("energii.in");
ofstream g("energii.out");

int n, w, i, j, wmin, s, min1;
int eg[1001], cg[1001];
int a[10001];

int main()
{
    f >> n >> w;
    wmin = w;
    for (i = 1; i <= n; i++)
        f >> eg[i] >> cg[i];
    for (i = 1; i <= n; i++)
        for (j = w; j >= 0; j--)
            a[j+eg[i]] = max(a[j+eg[i]], a[j]+cg[i]);

    for (i = w+1, min1 = a[w]; i <= 10000; i++)
        if (a[i] < min1 && a[i] != 0)
            min1 = a[i], wmin = i;

    if (min1 == 0)
        g << -1;
    else
        g << min1;
    return 0;
}