import sys
sys.setrecursionlimit(5*10**5)
input = sys.stdin.readline
from collections import defaultdict, deque, Counter
from heapq import heappop, heappush
from bisect import bisect_left, bisect_right
from math import gcd

n,m = map(int,input().split())
ans = -1
for i in range(n):
    v,w = map(int,input().split())
    if w <= m:
        ans = max(ans, v)

print(ans)