import java.util.*;
import java.lang.*;
import java.io.*;

// The main method must be in a class named "Main".
class Main {
    public static void main(String[] args) {
        Solution solution = new Solution();

        // =========================
        // 테스트 케이스 1
        // =========================
        int N1 = 4;
        int K1 = 7;
        
        int[][] items1 = {
            {6, 13},
            {4, 8},
            {3, 6},
            {5, 12}
        };
        
        int answer1 = solution.solution(N1, K1, items1);
        System.out.println(answer1);
        
    }
}