// URL: https://yukicoder.me/problems/no/817

import std;

version(unittest) {} else
void main()
{
  int N, K; io.getV(N, K);
  int[] A, B; io.getC(N, A, B);
  auto Am = A.dup; Am[] -= 1;
  auto Bp = B.dup; Bp[] += 1;

  auto z = Zaatsu!int(Am, A, B, Bp), c = new int[](z.n+1);
  foreach (Ai, Bi; lockstep(A, B)) {
    ++c[z.comp(Ai)];
    --c[z.comp(Bi+1)];
  }
  foreach (i; 0..z.n)
    c[i+1] += c[i];

  foreach (i, ci; c[0..$-1]) {
    auto j = i.to!int;
    auto m = ci*(z.uncomp(j+1)-z.uncomp(j));
    if (K > m) {
      K -= m;
    } else {
      io.put!"{exit: true}"(z.uncomp(j) + (K-1)/ci);
    }
  }
}

struct Zaatsu(T)
{
  const size_t n;

  pure nothrow @safe
  {
    this(U...)(U v)
    {
      T[] d;
      foreach (w; v) d ~= w.array;
      auto u = d.sort.uniq;
      n = u.walkLength;
      c2 = new T[](n);

      foreach (i, ui; u.enumerate(0)) {
        c1[ui] = i;
        c2[i] = ui;
      }
    }

    int comp(T v) const
    {
      return c1[v];
    }
    auto comp(R)(R v) const
      if (isInputRange!R)
    {
      return v.map!(w => c1[w]);
    }

    T uncomp(int v) const
    {
      return c2[v];
    }
    auto uncomp(R)(R v) const
      if (isInputRange!R)
    {
      return v.map!(w => c2[w]);
    }
  }

  //private
  //{
    int[T] c1;
    T[] c2;
  //}
}

auto io = IO!()();
struct IO(alias IN = stdin, alias OUT = stdout)
{
  import core.stdc.stdlib : exit;

  void getV(T...)(ref T v)
  {
    foreach (ref w; v) get(w);
  }
  void getA(T)(size_t n, ref T v)
    if (hasAssignableElements!T)
  {
    v = new T(n);
    foreach (ref w; v) get(w);
  }
  void getC(T...)(size_t n, ref T v)
    if (allSatisfy!(hasAssignableElements, T))
  {
    foreach (ref w; v) w = new typeof(w)(n);
    foreach (i; 0..n) foreach (ref w; v) get(w[i]);
  }
  void getM(T)(size_t r, size_t c, ref T v)
    if (hasAssignableElements!T && hasAssignableElements!(ElementType!T))
  {
    v = new T(r);
    foreach (ref w; v) getA(c, w);
  }
  template getS(E...)
  {
    void getS(T)(size_t n, ref T v)
    {
      v = new T(n);
      foreach (ref w; v) foreach (e; E) mixin("get(w."~e~");");
    }
  }

  const struct PutConf
  {
    bool newline = true, flush, exit;
    string floatFormat = "%.10f", delimiter = " ";
  }

  void put(alias conf = "{}", T...)(T v)
  {
    putMain!conf(v);
  }
  void putB(alias conf = "{}", S, T)(bool c, S t, T f)
  {
    if (c) put!conf(t);
    else put!conf(f);
  }
  void putRaw(T...)(T v)
  {
    OUT.write(v);
    OUT.writeln;
  }

  private
  {
    dchar[] buf;
    auto sp = (new dchar[](0)).splitter;

    void nextLine()
    {
      IN.readln(buf);
      sp = buf.splitter;
    }
    void get(T)(ref T v)
    {
      if (sp.empty) nextLine();
      v = sp.front.to!T;
      sp.popFront();
    }

    void putMain(alias conf, T...)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      foreach (i, w; v) {
        putOne!conf(w);
        if (i+1 < v.length) OUT.write(c.delimiter);
      }
      static if (c.newline) OUT.writeln;
      static if (c.flush) OUT.flush();
      static if (c.exit) exit(0);
    }
    void putOne(alias conf, T)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      static if (isInputRange!T && !isSomeString!T) putRange!conf(v);
      else static if (isFloatingPoint!T) OUT.write(format(c.floatFormat, v));
      else static if (hasMember!(T, "fprint")) v.fprint(OUT);
      else OUT.write(v);
    }
    void putRange(alias conf, T)(T v)
    {
      mixin("const PutConf c = "~conf~";");
      auto w = v;
      while (!w.empty) {
        putOne!conf(w.front); w.popFront();
        if (!w.empty) OUT.write(c.delimiter);
      }
    }
  }
}