#include <iostream>
#include <fstream>
using namespace std;

int main()
{int m,n,v[100],c[100],i,ok,mini;
ifstream f("energii.in");
ofstream g("energii.out");
f>>n;
f>>m;
for(i=1;i<=n;i++)
{
    f>>v[i]>>c[i];
}
ok=0;
for(i=1;i<=n;i++)
{
    if(v[i]>=m)
    {
        mini=c[i];
        ok=1;
    }
}
for(i=1;i<=n;i++)
{
    if((v[i]>=m)&&(c[i]<mini))
    {
      mini=c[i];
    }
}
if(ok==0)
{
    g<<-1;
}
else
{
    g<<mini;
}
    return 0;
}