#include <bits/stdc++.h>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");

int n, G, dp[20005], mi = INT_MAX;
struct date {
    int w, p;
} a[10005];

int main()
{
    f >> n >> G;
    for (int i=1; i<=n; ++i)
        f >> a[i].w >> a[i].p;

    for (int i=1; i<=20000; ++i)
        dp[i] = INT_MAX;
    dp[0] = 0;
    for (int i=1; i<=n; ++i)
        for (int j=G; j>=0; --j)
            if (dp[j] != INT_MAX) {
                dp[ j+a[i].w ] = min (dp[ j+a[i].w ], dp[j] + a[i].p);
                if (j+a[i].w >= G && dp[ j+a[i].w ] < mi)
                    mi = dp[ j+a[i].w ];
            }
    if (mi == INT_MAX)
        g << -1;
    else  g << mi;
    return 0;
}