l = map(int, raw_input().split())
a=[]
b=[]
for n in xrange(l[0]):
    m = map(int, raw_input().split())
    a.append(int(m[0]))
    b.append(int(m[1]))
amax=max(a)
bsum=int()
bcos=0
for n in xrange(l[0]):
    if b[n]>=amax:
        bsum+=b[n]
        bcos+=1
d=(l[1]-bsum)//amax
if (l[1]-bsum)%amax !=0:
    d+=1
d+=bcos
print d
