N,H = [int(x) for x in input().split()]
a = [[int(x) for x in input().split()] for _ in range(N)]
ma = max(a,key = lambda x:x[0])[0]
cnt = 0
su = 0
for i in range(N):
  if a[i][1]>=ma:
    cnt+=1
    su += a[i][1]
H -= su
cnt+= H//ma
print(cnt)