#include<fstream>
using namespace std;
ifstream fin("energii.in");
ofstream fout("energii.out");
int main()
{
	int G,W,EGi,CGi,Cmin=10001,i;
	fin>>G;
	fin>>W;
	for(i=1;i<=G;i++){
		fin>>EGi>>CGi;
		if(CGi<Cmin){
			Cmin=CGi;
			fout<<Cmin;
		}
		else if(CGi<W)fout<<-1;
	}
	fin.close();
	fout.close();
	return 0;
}