import math
N,H=map(int,input().split())
A=[]
B=[]
for i in range(N):
  a,b=map(int,input().split())
  A.append(a)
  B.append(b)
  
B.sort(reverse=True)
max_a = max(A)
min_count = math.ceil(H / max_a)

H2 = max_a * min_count
for b in B:
    if max_a < b:
        H2 += b - max_a
        k = (H2 - H) // max_a
        min_count -= k
        H2 -= max_a * k
    else:
        break
print(min_count)
