#include<bits/stdc++.h>
using namespace std;
int main(){
    int n,R,maxn=-1,a[100000],b[100000];
    cin>>n>>R;
    for(int i=1;i<=n;i++){
        cin>>a[i]>>b[i];
        if(R>=b[i]&&a[i]>maxn)
        maxn=max(a[i],maxn);
        
    }
cout<<maxn;
    return 0;
    
    
    
}