#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef size_t ull;
typedef vector<int> vc;
typedef vector<vector<int>> matrix;
#define ft(n) for(int i=1; i<=n; i++)
#define sp ' '
#define vx first
#define vy second
string file = "energii";
ifstream f(file + ".in");
ofstream g(file + ".out");

int n, G, P;
vector<int> p, w;
vector<vector<int>> dp;

void init()
{
    f >> n >> P;
    p.resize(n + 1, 0);
    w.resize(n + 1, 0);
    ft(n)
    {
        f >> p[i] >> w[i];
        G = max(G, w[i]);
    }

    dp.resize(2, vc(G + 1, 0));
}

int proc()
{
    for (int i = 1; i <= n; i++)
    {
        for (int j = 0; j <= G; j++)
        {
            dp[i % 2][j] = dp[(i - 1) % 2][j];
            if (j >= w[i])
                dp[i % 2][j] = max(dp[i % 2][j], dp[(i - 1) % 2][j - w[i]] + p[i]);
        }
    }
    for (int j = 1; j <= G; j++)
    {
        dp[0][j] = max(dp[0][j], dp[1][j]); //doesn't need the newest values, just the biggest
        if (dp[0][j] >= P) return dp[0][j];
    }
    return -1;
}


int main()
{
    init();
    g << proc();
    return 0;
}