import java.util.Scanner; import java.util.TreeMap; public class Main { public static void main(String[] args) throws Exception { Scanner sc = new Scanner(System.in); int n = sc.nextInt(); int k = sc.nextInt(); int[] a = new int[n]; int[] b = new int[n]; for (int i = 0; i < n; i++) { a[i] = sc.nextInt(); b[i] = sc.nextInt(); } sc.close(); TreeMap map = new TreeMap(); for (int i = 0; i < n; i++) { if (map.containsKey(a[i])) { map.put(a[i], map.get(a[i]) + 1); } else { map.put(a[i], 1); } if (map.containsKey(b[i])) { map.put(b[i], map.get(b[i]) - 1); } else { map.put(b[i], -1); } } int prev = 0; for (int key : map.keySet()) { prev = map.get(key) + prev; map.put(key, prev); } int prevK = map.firstKey(); long prevV = map.get(prevK); map.pollFirstEntry(); long cnt = 0; for (int key : map.keySet()) { if (cnt + prevV * (key - prevK) >= k) { long x = (k - 1 - cnt) / prevV + prevK; System.out.println(x); break; } else { cnt += prevV * (key - prevK); prevK = key; prevV = map.get(prevK); } } } }