自己看

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,k;
int main(){
	//freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
	cin>>n>>k;
    vector<ll> a(n,0);
    for(ll i=0;i<n;i++) cin>>a[i];
    auto ans=upper_bound(a.begin(),a.end(),k);
    if(ans==a.begin()){
        cout<<-1<<endl;
    }else{
        cout<<*(ans-1)<<endl;
    }
	//fclose(stdin);
	//fclose(stdout);
	return 0;
}
//coder::by::M91