#include<bits/stdc++.h>
using namespace std;
const int N=100010;
int h[N],w[N];
int num(int hi,int wi,int x)
{
    if(x>min(hi,wi))return 0;
    return (hi/x)*(wi/x);
}
int main()
{
    int x=1e5;
    int n,K;cin>>n>>K;
    for(int i=0;i<n;i++)
    {
        scanf("%d %d\n",&h[i],&w[i]);
    }
    int l=1,r=1e5;
    while(l<r)
    {

        int mid=(l+r)/2+1;
        int sum=0;
        for(int i=0;i<n;i++)
        {
            sum+=num(h[i],w[i],mid);
        }
        if(sum>=K)l=mid;
        else r=mid-1;
    }
    cout<<l<<endl;
    return 0;
}