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#include <stdio.h>
#include <vector>
#include <map>
#include <unordered_set>
#include <queue>
#include <unordered_map>
#include <math.h>
#include <limits.h>
#include <algorithm>
#include <functional>
#include <iterator>
#include <algorithm>
#include <string>
#include <iostream>

using namespace std;

#define pb push_back
#define mp make_pair

typedef long long ll;
typedef unsigned long long ull;

using namespace std;

int a[2000][2000];

void evaluate(int i, int j, int maxj) {
  if (j == maxj-1) {
    a[i][j] = a[i-1][j-1] + 1;
  } else if (j == 0) {
    a[i][j] = a[i-1][j] + 1;
  } else {
    int upper = a[i-1][j-1] + a[i-1][j];
    int double_upper = i > 1 ? a[i-2][j-1] : 0;
    a[i][j] = upper - double_upper + 1;
  }
}

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);

  int n, k, year;
  cin >> n >> k;

  int maxj=2;
  int answer = 0;
  cin >> answer;
  a[0][0] = 1;
  for (int i=1; i<n; ++i) {
    for (int j=0; j<maxj; ++j) {
      cin >> year;
      evaluate(i, j, maxj);
      if (a[i][j] <= k) {
        answer = min(answer, year);
      }
    }
    maxj++;
  }

  // for (int i=0; i<n; ++i) {
  //   for (int j=0; j<n; ++j) {
  //     cout << a[i][j] << " ";
  //   }
  //   cout << endl;
  // }

  // cout << "----------------" << endl;

  cout << answer << endl;

  return 0;
}