import sys, time, random
from collections import deque, Counter, defaultdict
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

n, w = mi()
ans = -1
for _ in range(n):
    x, y = mi()
    if y <= w:
        ans = max(ans, x)
print(ans)