mport math
n,m=[int(i) for i in input().split()]
a=[]
b=[]
for i in range(n):
  a0,b0=[int(i) for i in input().split()]
  a.append(a0)
  b.append(b0)
a.sort(reverse=True)
b.sort(reverse=True)
x=0
while m>0:
  if b==[]:
    x+=math.ceil(m/a[0])
    break
  else:
    if b[0]>a[0]:
      m-=b[0]
      del b[0] 
      x+=1
    else:
      x+=math.ceil(m/a[0])
      break
    
print(x)