#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    int nrgen,min,cn,cep,i,answ=-1;
    float var;
    ifstream in("energii.in");
    ofstream out("energii.out");
    in>>nrgen>>min;
    in>>cep>>cn;
    for(i=1;i<=nrgen;i++)
    {
     var=1.0*cn/cep;
     if(1.0*cn/cep>=var&&cn>=min)
     answ=cn;
     in>>cep>>cn;
     }
     out<<answ;
     in.close();
     out.close();
    }