N, H = map(int, input().split())
bs = []
maxA = 0
ans = 0
for _ in range(N):
    a, b = map(int, input().split())
    maxA = max(maxA, a)
    bs.append(b)
    
for b in bs:
    if b > maxA:
        H -= b
        ans += 1

print(ans + (H-1)//maxA+1)