#include <fstream>
#include <algorithm>
using namespace std;
const int NMAX = 1000;
int n, w, c[NMAX + 2], p[NMAX + 2], dp[NMAX + 2][NMAX + 2], i, j, s;
int main() {
    ifstream cin("energii.in");
    ofstream cout("energii.out");
    cin >> n >> w;
    for(i = 1; i <= n; ++i)
        cin >> p[i] >> c[i], s += c[i];
    for(i = 1; i <= n; ++i) {
        for(j = 0; j <= s; ++j) {
            if (j >= c[i]) {
                dp[i][j] = max(dp[i - 1][j], dp[i][j - c[i]] + p[i]);
            } else {
                dp[i][j] = dp[i - 1][j];
            }
            
        }
    }
    for(i = 1; i <= s; ++i)
        if(dp[n][i] >= w) {
            cout << i << "\n";
            return 0;
        }
    cout << "-1\n";
    return 0;
}