def main():

    N, H = map(int, input().split())
    A = []
    B = []
    count = 0
    for _ in range(N):
        a, b = map(int, input().split())
        A.append(a)
        B.append(b)
    swing = max(A)
    for i in range(N):
        if B[i] > swing:
            if H >= 0:
                H -= B[i]
                count += 1
            else:
                break
    if H >= 0:
        swingCount = -(-H // swing)
    else:
        swingCount = 0

    count += swingCount 

    print(count)

if __name__ == "__main__":
    main()