import math
n,h=map(int,input().split())
A=[0]*n
B=[0]*(n+1)
for i in range(n):
  A[i], B[i] = map(int, input().split())
a=max(A)
B.sort(reverse=True)
cnt=0
while h > 0:
  if a > B[0]:
    cnt+=math.ceil(h/a)
    h-=math.ceil(math.ceil(h/a)*a)
  else:
    cnt+=1
    h-=B[0]
    B.pop(0)
print(cnt)