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.append(0)
A.sort()
B.sort()
ans = 0
while A[-1] < B[-1]:
    b = B.pop()
    H -= b
    ans += 1
ans += (H+A[-1]-1)//A[-1]
print(ans)
