N, H = map(int, input().split())
ma = 0
B = []
for _ in range(N):
    a, b = map(int, input().split())
    ma = max(ma, a)
    B.append(b)
B = sorted([b for b in B if b > ma])
ans = 0
while H > 0 and B:
    H -= B.pop()
    ans += 1
if H > 0:
    ans += -(-H//ma)
print(ans)