haybale.java

import java.io.*;
import java.util.*;
public class haybale {
    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int n = Integer.parseInt(st.nextToken());
        long need = Long.parseLong(st.nextToken());
        long[] f = new long[n];
        long[] s = new long[n];
        for(int i = 0; i < n; i++) {
            st = new StringTokenizer(br.readLine());
            f[i] = Long.parseLong(st.nextToken());
            s[i] = Long.parseLong(st.nextToken());
        }
        int left = 0;
        long ret = Long.MAX_VALUE;
        TreeMap<Long, Integer> seen = new TreeMap<Long, Integer>();
        long flavor = 0;
        for(int i = 0; i < n; i++) {
            flavor += f[i];
            update(seen, s[i], 1);
            while(flavor - f[left] >= need) {
                update(seen, s[left], -1);
                flavor -= f[left++];
            }
            if(flavor >= need) {
                ret = Math.min(ret, seen.lastKey());
            }
        }
        pw.println(ret);
        pw.close();
    }
    private static void update(Map<Long, Integer> m, long k, int v) {
        if(!m.containsKey(k)) {
            m.put(k, 0);
        }
        int nv = m.get(k) + v;
        if(nv == 0) {
            m.remove(k);
        }
        else {
            m.put(k, nv);
        }
    }
}