dbflag=""

def debug(*args):
	if ""!=dbflag: print(*args)

if ""!=dbflag: _INDATA=open(dbflag)

def readline():
	if ""!=dbflag:return _INDATA.readline()
	else: return input()


result = -1


N, H = map(int, readline().split())



#２次元配列
import numpy as np
data=np.ndarray(shape=(N,2),dtype=int)


for i in range(0,N):
	data[i,:]=[int(x) for x in readline().split(' ')]

maxi=np.argmax(data[:,0])
amax=data[maxi,0]

B=data[:,1]
BoverA=B[B > amax]
lenBoverA=len(BoverA)
sumBoverA=np.sum(BoverA)

import math
cntA=math.ceil((H - sumBoverA ) / amax)

result = cntA + lenBoverA
debug("XX ",BoverA)
debug(data)
debug(data[:,1])
print(result)

