#include<fstream>
#include<cmath>
using namespace std;
ifstream f("energii.in");
ofstream g("energii.out");
const short d=1001;
int main()
{	
	short a[d][d],G,W,cmin=-1,i,j;
	f>>G;
	f>>W;
	for(i=1;i<=G;i++)
		for(j=1;j<=2;j++)
			f>>a[i][j];
	{
		for(i=1;i<G;i++)
			for(j=1;j<=2;j++)
		{
			if(a[i][1]>=W)
				cmin=a[i][2];
				else
					if(a[i+1][1]>=W)
						cmin=a[i+1][2];
			if(a[i+1][1]>=W)
				if(cmin>=a[i+1][2])
					cmin=a[i+1][2];
					
			
		}
	}
					
		g<<cmin;
	return 0;
}