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)

maxA = max(A)
cnt = 0
for b in B:
    if b > maxA and H > 0:
        H -= b
        cnt += 1
        
if H > 0:
    cnt += - (- H // maxA)

print(cnt)