import algorithm
import options
import sequtils
import sets
import std/heapqueue
import std/math
import std/tables
import strformat
import strutils

const letter: string = "abcdefghijklmnopqrstuvwxyz"
const Letter: string = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
const MAX_INT: int = high(int)
const MIN_INT: int = low(int)

proc scanf(formatstr: cstring){.header: "<stdio.h>", varargs.}
proc getchar(): char {.header: "<stdio.h>", varargs.}
proc nextInt(): int = scanf("%lld", addr result)
proc nextInts(n: int): seq[int] =
    var res = newSeq[int](n)
    for i in 0..<n:
        res[i] = nextInt()
    return res

proc nextInt64(): int64 = scanf("%lld", addr result)
proc nextUInt64(): uint64 = scanf("%lld", addr result)
proc nextFloat(): float = scanf("%lf", addr result)
proc nextString(): string =
    var get = false
    result = ""
    while true:
        var c = getchar()
        if int(c) > int(' '):
            get = true
            result.add(c)
        else:
            if get: break
            get = false

func toInt(b: bool): int =
    if b:
        return 1
    else:
        return 0

func `+`(a: int, b: bool): int = a + (b.toInt)
func `+`(a: bool, b: int): int = (a.toInt) + b
func `-`(a: int, b: bool): int = a - (b.toInt)
func `-`(a: bool, b: int): int = (a.toInt) - b
func `*`(a: int, b: bool): int = a * (b.toInt)
func `*`(a: bool, b: int): int = (a.toInt) * b

proc `|=`(a: var bool, b: bool) =
    a = a or b
func `|`(c1, c2: int): int = c1 or c2

proc `&=`(a: var bool, b: bool) =
    a = a and b
func `&`(c1, c2: int): int = c1 and c2

func `//`(a, b: int): int = a div b

proc `//=`(a: var int, b: int) =
    a = a div b

func `%`(a: int, b: Positive): int =
    result = a mod b
    if result < 0:
        result += b

proc `%=`(a: var int, b: int) =
    a = a mod b

func `<<`(a: int, s: int): int = a shl s
func `>>`(a: int, s: int): int = a shr s
proc `>>=`(a: var int, b: int) =
    a = a shr b

# Z/mo Z荳翫・a縺ｮ騾・・
func inv(a, mo: int): int =
    var r = (mo, a)
    var x = (0, 1)
    while r[1] != 0:
        x = (x[1], (x[0] - (r[0] div r[1]) * x[1]) % mo)
        r = (r[1], r[0] % r[1])

    if r[0] == 1:
        return x[0]
    else:
        return -1

func bitLength(n: Natural): int =
    result = 0
    var num = abs(n)
    while num > 0:
        result += 1
        num = num shr 1

proc chmax[T](a: var T, vars: varargs[T]): bool {.discardable.} =
    let target = max(vars)
    if a < target:
        a = target
        return true
    else:
        return false

proc chmin[T](a: var T, vars: varargs[T]): bool {.discardable.} =
    let target = min(vars)
    if a > target:
        a = target
        return true
    else:
        return false

template present(a: typed): bool = a.len != 0
template empty(a: typed): bool = a.len == 0

template rep(idx: untyped, n: SomeOrdinal, act: untyped): untyped =
    for idx in 0 ..< n:
        act

template loop(body: untyped): untyped =
    while true:
        body

func Yn(cond: bool, yes: string = "Yes", no: string = "No"): string =
    if cond:
        yes
    else:
        no

func `<`[T](u, v: openArray[T]): bool =
    assert u.len == v.len
    for j in 0..<u.len:
        if u[j] != v[j]:
            return u[j]-v[j] < 0

    return true

# start coding
let
    N = nextInt()
    W = nextInt()

var res = -1
rep(i, N):
    let
        vi = nextInt()
        wi = nextInt()
    if wi <= W:
        chmax(res, vi)

echo res