N, W  = map(int, input().split())
Q =[]
ans =-1
for item in range(N):
	v, w = map(int, input().split())
	Q.append([w, v])
	# TODO: write code...
Q.sort(reverse=True)
for w, v in Q:
	if w > W: continue
	ans = max(ans, v)
print(ans)