Buggy python submission (verdict: Time Limit Exceeded):
from operator import itemgetter

attackCount = 0

N, H = map(int, raw_input().split())
swords = []

for _ in xrange(N):
    swords.append(map(int, raw_input().split()))


swords.sort(key=itemgetter(0), reverse=True)
niceWeapon = swords.pop(0)

subWeapons = [x for x in swords if x[1] > niceWeapon[0]]
subWeapons.sort(key=itemgetter(1), reverse=True)

practicalHP = H
niceWeaponExist = True
if subWeapons and niceWeapon[1] > subWeapons[0][1]:
    practicalHP -= niceWeapon[1]
    attackCount += 1
    niceWeaponExist = False

if practicalHP <1:
    print attackCount
else:
    while practicalHP > 0 and subWeapons:
        if niceWeaponExist and niceWeapon[1] > subWeapons[0][1]:
            attackCount += 1
            practicalHP -= niceWeapon[1]
            niceWeaponExist = False
        else:
            throwWeapon = subWeapons.pop(0)
            attackCount += 1
            practicalHP -= throwWeapon[1]

    if practicalHP > 0 and niceWeaponExist:
            attackCount += 1
            practicalHP -= niceWeapon[1]
            niceWeaponExist = False
    if practicalHP > 0:
        attackCount += (practicalHP / niceWeapon[0])
        if practicalHP % niceWeapon[0]:
            attackCount += 1

    print attackCount


Fixed submission:
from operator import itemgetter

N, H = map(int, raw_input().split())
attackCount = 0

swords = []
for _ in xrange(N):
    swords.append(map(int, raw_input().split()))
swords.sort(key=itemgetter(0), reverse=True)
niceWeapon = swords[0]

subWeapons = [x for x in swords if x[1] > niceWeapon[0]]
subWeapons.sort(key=itemgetter(1), reverse=True)

practicalHP = H

while practicalHP > 0 and subWeapons:
    throwWeapon = subWeapons.pop(0)
    attackCount += 1
    practicalHP -= throwWeapon[1]

if practicalHP > 0:
    attackCount += (practicalHP / niceWeapon[0])
    if practicalHP % niceWeapon[0]:
        attackCount += 1

print attackCount

Buggy python submission (verdict: Runtime Error):
 itemgetter

attackCount = 0

N, H = map(int, raw_input().split())
swords = []

for _ in xrange(N):
    swords.append(map(int, raw_input().split()))


swords.sort(key=itemgetter(0), reverse=True)
niceWeapon = swords.pop(0)

subWeapons = [x for x in swords if x[1] > niceWeapon[0]]
subWeapons.sort(key=itemgetter(1), reverse=True)

practicalHP = H
niceWeaponExist = True
if subWeapons and niceWeapon[1] < subWeapons[0][1]:
    practicalHP = H - niceWeapon[1]
    attackCount += 1
    niceWeaponExist = False

if practicalHP <1:
    print attackCount
else:
    while practicalHP > 0 and subWeapons:
        if niceWeaponExist and niceWeapon[1] > subWeapons[0][1]:
            attackCount += 1
            practicalHP -= niceWeapon[1]
            niceWeaponExist = False
        else:
            throwWeapon = subWeapons.pop(0)
            attackCount += 1
            practicalHP -= throwWeapon[1]

    if practicalHP > 0:
        if niceWeaponExist:
            attackCount += 1
            practicalHP -= niceWeapon[1]
            niceWeaponExist = False
    if practicalHP > 0:
        attackCount += (practicalHP / niceWeapon[0])
        if practicalHP % niceWeapon[0]:
            attackCount += 1

    print attackCount


Fixed submission:
from operator import itemgetter

N, H = map(int, raw_input().split())
attackCount = 0

swords = []
for _ in xrange(N):
    swords.append(map(int, raw_input().split()))
swords.sort(key=itemgetter(0), reverse=True)
niceWeapon = swords[0]

subWeapons = [x for x in swords if x[1] > niceWeapon[0]]
subWeapons.sort(key=itemgetter(1), reverse=True)

practicalHP = H

while practicalHP > 0 and subWeapons:
    throwWeapon = subWeapons.pop(0)
    attackCount += 1
    practicalHP -= throwWeapon[1]

if practicalHP > 0:
    attackCount += (practicalHP / niceWeapon[0])
    if practicalHP % niceWeapon[0]:
        attackCount += 1

print attackCount