import java.util.Scanner;

public class Main {
    static int N=100010;
    static int[] h=new int[N];
    static int[] w=new int[N];
    static int n,k;
    public static void main(String[] args) {
        Scanner in =new Scanner(System.in);
        n=in.nextInt();
        k=in.nextInt();
        for(int i=0;i<n;i++){
            h[i]=in.nextInt();
            w[i]=in.nextInt();
        }

        int l=1,r=100000;
        while (l<r){
            int mid=(l+r+1)/2;//找最大边长
            if(check_mid(mid)){
                l=mid;
            }else {
                r=mid-1;
            }
        }
        System.out.println(r);
    }

    static boolean check_mid(int mid){
        int res=0;
        for(int i=0;i<n;i++){
            res+=(h[i]/mid)*(w[i]/mid);//原有面积除目标面积等于块数.
            if(res>=k)
                return true;
        }
        return false;
    }
}