#include <iostream>

using namespace std;

int main()
{int n,m,ok,mini,v[100],a[100],i,on;
cout<<"n=";cin>>n;
cout<<"m=";cin>>m;
for(i=1;i<=n;i++)
{
    cout<<"v["<<i<<"]=";cin>>v[i];
}
for(i=1;i<=n;i++)
{
    cout<<"a["<<i<<"]=";cin>>a[i];
}
ok=0;
i=1;
while((ok==0)&&(i<=n))
{
    if(v[i]>=mini)
    {
        mini=a[i];
        ok=1;
    }
    i++;
}
on=0;
for(i=1;i<=n;i++)
{
    if(v[i]>=m)
    {
        if(mini<=a[i])
        {
            mini=a[i];
            on=1;
        }
    }
}
if(on==1)
{
    cout<<mini;
}
else
    cout<<"-1";
    return 0;
}